Different cloud models are explained below:
Private cloud: The cloud infrastructure is operated solely for an organization. It may be managed by the organization or a third party and may exist on premise or off premise.
Community cloud: The cloud infrastructure is shared by several organizations and supports a specific community that has shared concerns (e.g. mission, security requirements, policy, and compliance considerations). It may be managed by the organizations or a third party and may exist on premise or off premise.
Public cloud: The cloud infrastructure is made available to the general public or a large industry group and is owned by an organization selling cloud services.
Hybrid cloud: A hybrid cloud includes both the public and private options with one or more providers. By spreading things out over a hybrid cloud, you can keep good control of security and optimize costs. The downside is that you have to keep track of multiple security platforms and ensure that all aspects of your business can communicate with each other.
IAAS (Infrastructure as a Service) : A business may not want to invest into datacenters, servers, networking equipment and the manpower required to maintain all these resources. They may wish to utilize more computer resources as they grow. This is where the Infrastructure as a Service (IAAS) comes in.
SAAS(Software as a Service): also referred to as software on demand, can be used by many people for a variety of functions. It allows users to benefit from the functionality of particular software without having to worry about storage or other issues. The software can easily be accessed by multiple users using just a web browser. Google Docs is a great example of SAAS.
PAAS (Platform as a Service): is a variant of SAAS. A client runs their own copies of the Operating System, using the cloud provider's infrastructure. Clients don't have to worry about storage spaces and maintaining servers or hard disks.
NAAS(Network as a Service): Network as a Service (NaaS) is a business model that aims at providing network services over the internet. From a client's point of view, they only require a computer that is connected to the internet - along with the access to NAAS provider's portal.