A service is any object that is registered in the OSGi Service Registry and can be looked up using its interface name(s). The only prerequisite is that a service should implement some interface.
A "component" tends to be an object whose lifecycle is managed, usually by a component framework such as Declarative Services (DS), Blueprint or iPOJO. See this page on the OSGi Community Wiki for a discussion of the different component frameworks available.
A component may have any of the following features, in combination or alone:
- A component may be started and stopped; this would be considered an "active" component, though that is also an informal term. A component that doesn't need to be started or stopped is called passive.
- A component may publish itself as an OSGi service.
- A component may bind to or consume OSGi services.
