Public Cloud vs Private Cloud: What is the Difference?

The key difference between public and private cloud computing relates to access. In a public cloud, organizations use shared cloud infrastructure, while in a private cloud, organizations use their own infrastructure. To fully understand which cloud environment organizations should use, it is important to understand each environment in-depth, as well as their advantages and disadvantages.

What is a Public cloud?

In a public cloud model, cloud services and resources are offered through a third-party cloud service provider (CSP) and delivered via the internet through a subscription model, such as platform-as-a-service (PaaS), infrastructure-as-a-service (IaaS) or software-as-a-service (SaaS). In this model, all hardware, software, and other supporting cloud infrastructure are owned, operated and maintained by the cloud provider and shared with other users. Examples of public clouds include Amazon Web Services (AWS), Microsoft Azure and Google Cloud Platform (GCP).

The public cloud operates on the principle of multi-tenancy, which means that multiple organizations, or “tenants”, have access to the same cloud infrastructure and computing resources, such as servers and cloud storage.

What is a Private Cloud?

A private cloud, which is sometimes referred to as an on-premises private data center, is a cloud computing model where one organization has exclusive use of the cloud, its services and associated infrastructure. While a private cloud may still be hosted by a CSP, it is dedicated to just one user and resources are never shared.

Private clouds are most often used by organizations that require customizable and highly secure IT environments. For example, private clouds are often used by government agencies, hospitals, or financial institutions, which maintain sensitive data and are subject to strict compliance standards.

Public vs Private Cloud: Advantages

Public vs Private Cloud: Disadvantages

What is a Hybrid Cloud

Because private and public cloud models offer inherent advantages (and disadvantages), many organizations are increasingly turning to a hybrid cloud model, which is an IT environment that combines elements of a public cloud, private cloud and on-premises infrastructure into a single, common, unified architecture. In a hybrid cloud environment, organizations have the option to run and scale workloads in the optimal setting, as well as the flexibility to move workloads between different environments quickly and easily.

For example, with a hybrid cloud model, organizations are able to leverage the public cloud for high-volume, low-risk activity, such as hosting web-based applications like email or instant messaging. Meanwhile the private cloud can be reserved for functions that require greater security, such as processing payments or storing personal data. In so doing, the organization is able to capitalize on the cost savings of a public cloud while also maintaining a higher level of security or compliance for select functions.

Advantages of a Hybrid Cloud Environment

With a hybrid cloud model, many organizations can get the “best of both worlds”. Advantages include:

• Flexibility: A hybrid cloud computing model allows the organization to run a workload in the optimal environment, as well as shift that workload based on capacity, demand or costs.
• Cost Efficiency: In a hybrid model, organizations can optimize their costs by selecting the best computing environment for each task.
• Elasticity: A hybrid cloud environment is dynamic, meaning that resources can quickly be adjusted and reallocated based on current needs. Further, in the case of unexpected surges in demand, the business can manage such spikes through a public cloud service.
• Business Agility: A unified hybrid cloud platform can help expand adoption of Agile and DevOps methodologies, which in turn can help speed time to market.
• Enhanced Security and Compliance: A unified hybrid cloud platform helps the organization take a holistic approach to cybersecurity and regulatory compliance. Since the organization is operating in a single IT environment, companies can develop a comprehensive strategy and deploy tooling consistently across the entire environment. A hybrid cloud approach also ensures that the organization properly hosts sensitive information, such as customer data or patient records, in a private cloud environment as dictated by government regulations or industry guidelines.

Hybrid Cloud vs. Multi Cloud

Though sometimes used interchangeably, hybrid and multi-cloud environments are two distinct models.

In short, a hybrid cloud creates a single environment consisting of public, private and on-prem infrastructure elements and services. A multi-cloud environment, on the other hand, unites two or more public cloud instances but does not integrate private cloud services or an on-prem component.

Based on this definition, it is possible for a hybrid cloud model to also be a multi-cloud model if the environment incorporates private cloud, on-prem and more than one public cloud instance.

Questions to Ask when Choosing a Deployment Option

As discussed above there are four main cloud deployment options:

1. Public cloud
2. Private cloud
3. Hybrid cloud
4. Multi-cloud

Organizations interested in shifting to a cloud-based business model will need to consider which deployment option best meets their needs. Some key considerations include:

Security

Every cloud environment has unique security challenges.

• Which aspects of the cloud environment will the organization be responsible for?
• Does the business have the necessary expertise and resources to maintain strong cloud security standards?
• How will the organization adjust its security strategy to protect cloud-based assets?

Regulatory compliance

• What industry or government regulations is the organization subject to?
• Does the preferred cloud model comply with those needs?
• Can the organization adopt a hybrid cloud strategy and shift certain services to a public cloud model while maintaining others in a more secure environment?

Scalability

• What are the organization’s near-term plans and how can the environment evolve to support those goals?
• Is speed and flexibility critical to the organization’s go-to-market strategy?

Reliability

• In the event of a network failure, how will services and workloads be impacted?
• Can the organization tolerate brief service interruptions?

Cost

• What is the cost associated with each of these models?
• What impact will the decision have on the business’s current IT organization?

Complexity

• How does shifting to the cloud impact business operations?
• How will the organization mitigate complexity related to the cloud migration?

Remote access

• Does the business need to support a remote or mobile workforce?
• Does the organization intend to allow remote work in the future?