Hybrid

A public cloud is a publicly accessible cloud environment owned by a cloud provider.

The facilities are generated for the general public and also for enterprises.

So anybody can access the public cloud on a pay per usage basis.  On demand, they can access whatever services are available.

The cloud service provider is responsible for the creation and  maintenance of the  cloud and its  resources.

A private cloud is owned by a single organization.

Enterprises may have sensitive data which they are not willing to share in the public environment.

So, they will create an environment  (i.e. Cloud ) for their own employees and for their personal usage.

Typically, this will be on-premise cloud.

Every organizations can have their own private cloud.

With a private cloud, the same organization is technically both the cloud consumer and cloud provider.

The data stored in the Private Cloud is more secure than the data in Public Cloud.

There will be situations where you will need to access the public cloud as well as the private cloud, so that they can maintain sensitive data in the private cloud and general data in the public cloud.

A hybrid cloud is a cloud environment comprised of two or more different cloud deployment models.

With Hybrid Cloud, both public access and private access is available for a specific enterprises.

Hybrid Cloud model can be complex and challenging to create and maintain due to the potential disparity in cloud environments and the fact that management responsibilities are typically split between the private cloud provider of the  organization and the public cloud service provider.

Sometimes two or more organizations want to share something viz. their work, projects data etc with each but at the same time, they do not want their data to be shared publicly.

In such a scenario, the Community cloud is used, wherein both the private cloud of each  enterprises are shared with each other forming a community..

Hence, a community cloud is similar to a public cloud except that its access is limited to a specific community of cloud consumers.