What’s the Difference Between Public Cloud and Private Cloud?
The terms private cloud and public cloud refer to the on-demand delivery of IT resources over a network. In a private cloud, a single organization controls and maintains the underlying infrastructure to deliver the IT resources. In a public cloud, external cloud providers deliver the resources as a fully managed service. For example, applications require computing resources like internal memory, data storage, and CPU.
Consider an organization with several departments, like finance and marketing, that need computing resources for their applications. In a private cloud setup, the organization purchases server hardware, maintains it in a central data center, and delivers these resources to the different departments over a network. Individual teams may additionally invest in software infrastructure like operating systems or database software for their applications. In a public cloud setup, teams can access everything they need to run their application as a fully managed service from an external public cloud provider. They have complete control over the resources they want to access as a service and the resources they want to purchase.
Similarities between private and public clouds
Amazon first introduced cloud services as Amazon Web Services (AWS). Our initial offerings focused on delivering compute and storage infrastructure over the network. After that, several large organizations attempted to replicate the cloud computing model on their internal infrastructure.
The term private cloud was introduced to distinguish between these internal cloud environments and third-party, public cloud services provided by organizations like us. Users of both public and private cloud services experience certain similarities. Here are some examples.
Infrastructure on demand
Both public and private clouds abstract and share computing resources like hardware, networks, software, servers, and storage over a network. Users can allocate and release resources as required, as well as manage infrastructure configurations like software modules.
For example, users can provision and configure several servers using software commands. Resource provisioning automatically scales up or down based on demand. There’s no scarcity or underutilization of resources.
Similar underlying technologies
Both types of cloud environments have similar underlying technologies. They use virtualization to abstract underlying hardware and deliver it using an API. Both models also provide automatic scaling, automated orchestration, fault resiliency, and improved backup systems.
However, for the most part, organizations have not truly succeeded in deploying a private cloud with features comparable to the public cloud.
Operational efficiency
Both public and private clouds introduce operational efficiency in an organization's IT infrastructure. Organizations save on costs by centralizing infrastructure management. Scaling speed increases and time to market for new products decreases. Utilization of existing capacity improves and costs lower.
In general, a public cloud brings much more operational efficiency across a range of use cases than the private cloud.
Key differences: public vs. private cloud
It’s almost impossible to replicate public cloud infrastructure privately. You get significantly more breadth and depth of services from public cloud providers because they’re fully dedicated to scaling and improving their offerings. You also get more innovation, access to a global community, and proven operational expertise.
Next, we discuss some other significant differences.
Infrastructure
Public cloud providers offer a range of infrastructure options at scale. They store infrastructure in data centers around the globe. You can access customized resources for specific geographies and computing needs.
Conversely, it’s challenging to privately replicate the range, scale, and quality of public cloud infrastructure. Private organizations have different priorities, so it’s easy for infrastructure to get outdated over time. In contrast, the sole focus of a public cloud provider is to maintain and manage infrastructure to the highest quality.
Security
Private cloud security depends on the deployment model. Organizations that host on-premises infrastructure are responsible for the physical security of the infrastructure they purchase.
You can also deploy private clouds on infrastructure that a third-party organization purchases and maintains in its data center. In such managed private clouds, security of the physical infrastructure is the responsibility of the third party. Either way, you’re responsible for securing your data and cloud environment from unauthorized access.
In public clouds, security is a shared responsibility between the cloud provider and the public cloud users. The public cloud provider is responsible for securing all hardware and software infrastructure they provide. You’re responsible for the security of your data and applications in the cloud.
Deployment
Private cloud deployments are complex and time-consuming. They require a significant upfront investment in infrastructure and human resources. You must source teams with advanced coding and engineering expertise to set up your private cloud environment.
In contrast, public cloud deployments are fast and easy. The cloud service provider often has a graphical UI that even non-technical team members can use to set up and manage the environment. There are no upfront costs or lock-in contracts. You often get to try the services for free before committing to scale.
Ongoing costs
The private cloud model proves to be expensive over time. You have to maintain and manage your private infrastructure. IT hardware like servers and disk storage require cooling, electricity, and ongoing physical security. You must also upgrade system software, and you need IT professionals to do so. You may even have to purchase new hardware regularly. For example, you may have to replace your hard disk drives (HDDs) with SSDs for better performance.
In contrast, public cloud resources are much more affordable and cost-effective. There are no maintenance costs, and you only pay for what you use. Expenditure is much lower and more predictable due to the economics of scale.
When to use public cloud vs. private cloud
Public cloud computing services are preferable for nearly every use case. They can provide all the underlying software and hardware infrastructure, so you can focus on your application development instead of the application's computing environment.
Public cloud computing services can also be serverless. This means you can build and run applications and services without managing infrastructure. Your application still runs on servers, but the third-party service provider does all the server management.
A private cloud deployment model is only suitable for very large organizations that already have multiple data centers and existing infrastructure management systems in place. They use private clouds to improve existing resource utilization. Even such organizations prefer a multicloud approach. They use specialized software to seamlessly move workloads between private and public cloud computing resources as needed.
Can you use both the public cloud and the private cloud?
Yes, you can set up a hybrid cloud environment with public cloud and private clouds to meet your specific requirements. A hybrid cloud is an IT infrastructure design that integrates a company’s internal IT resources with third-party cloud provider infrastructure and services. With a hybrid cloud, you can store your data and run your applications across multiple environments. You can also centrally provision, scale, and manage all your computing resources.
Can you run a private cloud in the public cloud?
Yes. A virtual private cloud is a private cloud that you can deploy within a public cloud infrastructure. It’s a secure, isolated environment where private cloud users can run code, host websites, store data, and perform other tasks that require a traditional data center. Virtual private clouds give you the convenience and scalability of public cloud computing resources alongside additional control and security.
Summary of differences: public cloud vs. private cloud
| Public cloud |
Private cloud |
|
| Setup |
A cloud provider manages and delivers IT infrastructure over the network for external use. |
A single organization manages and delivers IT infrastructure over the network for internal use. |
| Infrastructure |
Scale, variety, and quality of resources is very high. |
It’s not possible to privately replicate the range and scale of the public cloud. Infrastructure quality and variety is limited. |
| Security |
The cloud provider is responsible for the security of physical and virtual infrastructure. The user is responsible for the security of their data and applications. |
The organization is responsible for the security of the hardware and software infrastructure, as well as the data and applications. |
| Deployment |
Straightforward using API calls or few clicks on the graphical UI. |
Requires complex technologies and significant IT expertise. |
| Costs |
No upfront costs. Potentially free for a limited period or a limited usage range. Low ongoing costs based on exact usage due to economies of scale. |
High initial investment in hardware and software licensing. High ongoing costs for infrastructure maintenance, security, and upgrades. |
How can AWS support your public and private cloud requirements?
Amazon Web Services (AWS) offers more than 200 fully featured services from data centers globally. Millions of customers—including the fastest-growing start-ups, largest enterprises, and leading government agencies—use AWS to lower costs, become more agile, and innovate faster.
For example, with AWS as your public cloud provider, you get the following benefits:
- Significantly more services, and more features within those services, than any other cloud provider.
- Fully managed services in compute, storage, databases, analytics, artificial intelligence and machine learning (AI/ML), Internet of Things (IoT), and more. You can build applications for anything you can imagine.
- A flexible and secure cloud computing environment built to satisfy security requirements for the military, global banks, and other high-sensitivity organizations.
For any private cloud requirements, you can also run a virtual private cloud on AWS using Amazon Virtual Private Cloud (Amazon VPC). Amazon VPC gives you full control over your virtual networking environment, including resource placement, connectivity, and security.
Get started with cloud computing on AWS by creating an account today.
