Components vs. Services

Reference: <Pro WCF 4>

It is natural to be confused about the terms component and service, and what they mean. A component is a piece of compiled code that can be assembled with other components to build applications. Components can also be easily reused within the same application or across different applications. This helps reduce
the cost of developing and maintaining the application once the components mature within an organization. Components are usually associated with the object-oriented programming (OOP) paradigm.
A service is implemented by one or more components, and is a higher-level aggregation. Component reuse seems to work well inhomogeneous environments; service orientation fills the gap by establishing reuse in heterogeneousenvironments by aggregating one or more components into a service and making them accessible through messages using open standards. These service definitions are deployed with the service, and they govern the communication from the consumers of the service via various contracts and policies, among other things.