• Software as a Service – SaaS (Software as a Service). Cloud enables the consumer to use the provider’s applications running on cloud infrastructure. These applications are accessible from various client devices through either a thin client interface such as a web browser (e.g. web e-mail), or the program interface. The consumer does not manage or control  the basic cloud infrastructure including network, servers, operating systems, storage, or even individual functions of the application, with the possible exception of  limited specific user setting  of  application configuration .
• Platform as a Service – PaaS (Platform as a Service). Cloud enables the consumer to deploy self-developed or acquired applications to cloud infrastructure. These applications may have been developed  by means of   programming languages, libraries, services and tools supported by the provider.The consumer does not manage or control the basic cloud infrastructure (networks, servers, operation systems, storage) but he controls installed applications and  configuration for the guest application environment.
• Infrastructure as a Service – IaaS (Infrastructure as a Service). Cloud enables the consumer to process and  store data,  to use networks  as well as  other basic  computing resources  and thus  enabling him  to deploy and run arbitrary software, which can include operating systems and applications. The consumer does not manage or control the basic cloud infrastructure but has control over operating systems, repository and deployed  applications, or has limited control over  selected components in the network (e.g.  security gates and access points).

Some sources mention even more models of cloud services:

• Network as a Service – Naas
• Desktop as a Service – DaaS
• Management as a Service – Maas
• Business Process as a Service – BPaaS
• Information as a Service – INFaaS
• Everything as a Service – EaaS