Private cloud

The cloud infrastructure is operated, either on or off their premises, solely for an organization. Either the organization or a third party can manage it.

Public cloud

An organization that sells cloud services makes the cloud infrastructure available to the general public or a large industry group.

Hybrid

The cloud infrastructure is a composition of two or more clouds that remain unique entities but are bound together by standardized or proprietary technology that enables data and application portability (for example, cloud bursting for load-balancing between clouds).

Cloud is a shift in the consumption and delivery of IT with the goal of reducing costs, providing economies of scale, elastic scalability, and the introduction of automation and self-service. Although utilizing virtualization technology, cloud encompasses much more.
With private clouds deployments, all resources are owned and controlled by one private enterprise and those resources are usually housed on the client’s premise behind their firewall.

With public clouds, the resources are shared between multiple clients who pay only for the resources they use. Located off premise, these cloud services are an extension of a client’s IT infrastructure such as storage clouds.

And many features from private or public clouds can be combined to create hybrid clouds that address unique business needs. Different deployment models call for different infrastructures, which lead to different computing architectures. Due to different requirements and goals, each cloud architecture offers its own advantages and disadvantages.