What is the function of the source follower ?

Hi, all,
Who can tell me the difference between the source follower and buffer, as well as their functions?
Thank you all!

http://en.wikipedia.org/wiki/Common_drain
http://en.wikipedia.org/wiki/Buffer_amplifier

The source follower is also a buffer. But buffer is a broad definition for anything that amplifies a signal from a previous block and/or decouple it from the next stage.

In RF, buffers are generally used for driving long lines on chip. On the other hand, source followers are widely used for output RF matching. Additionally, source followers are also used as active inductors.