What is the difference between link building and link exchange?

When some one put a link in others site in order to get a link from that site it is called link bulding process.
When two sites agreed to exchange the links with each other it is called link exchange

Link building is process to build a link for your website at other sites. Link exchange is a process in which two sites are share links with each other.

Link building is process to build a link for your website at other sites. Link exchange is a process in which two sites are share links with each other.