Question

I think both @Component and @Service can be used to detect bean automatically, anyone can show me the difference between those two annotations?

Answer 1

The basic difference between both annotations is that @Service is a specialization of @Component.

See also spring documentation for @Service:

Indicates that an annotated class is a “Service” (e.g. a business
service facade).

This annotation serves as a specialization of @Component, allowing for
implementation classes to be autodetected through classpath scanning.

A specialization of component is also a @Repository and a @Controller

Further information can be found e.g. here.