How to find a table of differences and simularities of the 4 market
economies of pure monopolies, monopolistics competition, ologopolies
and pure competition?

There's exactly the table you're seeking at the Center for Learning
Technologies site:

www.clt.astate.edu/parmah/6003wk14.doc

Scroll down about a third of way down the file (which is in .doc
format -- if it presents any difficulties for you, let me know through
a Request for Clarification).

Hope this does the trick.