Computer Science/El Gamal and RSA

Discuss the difference between cipher encryption El Gamal and RSA.  Who created them and why?

The points that you will receive will depend on the quality of your post.  Points will be given when:

The source of the idea is clearly stated.
The comment clearly and successfully communicates the topic or issue.
Post clearly answers the question being asked.
Cite your source(s) of information.