After committing the 5 characteristics of Cloud to memory, there are three types of Cloud deployment to consider. These are Public, Private, and Hybrid. While you are looking at various cloud offerings, understanding these Deployment types will better enable you to determine how they might fit into your strategy. Here we go...
Public: This is a deployment that meets all 5 characteristics of the Cloud. Every service is shared across every tenant and user. Quality being equal, this is the most cost effective method. Keep in mind, not all vendors are created equal, and bigger may not mean better for what you are seeking to achieve.
Private: This is a deployment that fits all of the characteristics of cloud, except Multi-Tenancy. This is typically a deployment in a datacenter or on premise location where the cost of the entire solution is absorbed by one customer or tenant. I've heard arguments that business units within a company perhaps larger than a give cloud service constitute multi-tenant. Bottom line, if one company is paying the tab, its Private, not Public and the lack of multi-tenancy is a disadvantage.
Hybrid: This is a deployment that is a mix of a Public and Private clouds. It is not a Public cloud integrated with an on premise, traditional "non-cloud" LAN. With all due respect, that would be a hybrid of a cloud and non-cloud LAN; and the overall solution is likely unable to leverage the 5 characteristics of cloud and the resulting benefits.
In Summary, you can have any quantity of cloud solutions, with varying levels of integration being used by a given company. This raises a number of other considerations, including the use of a cloud aggregator or integrator. In the context of this post however, those would just expand the services and still fall into one of the above three types. I'll get into more details and examples of these types in the future.