Is it Peer or Colleague?

Today, here at Enterprise Hive, we got into a discussion on  the meaning of the words "Peer" and "Colleague".  We all had a little bit different definition so I thought we should ask our edu1world members how they defined these two words.

So in your opinion, how do you differentiate between a Peer and Colleague?

What criteria do you use to qualify a college or university as a "Peer Institution"?

Looking forward to your res...