Polk Monitor 40 vs Polk RTi6?

Putting together a system for the first time. For whatever reason, I'm looking at these speakers, price seems reasonable and quality sounds o.k. Also, I am getting tired of looking and would like to buy something. Is there much difference between the two speakers I've mentioned? Thanks I appreciate any responses.

As an owner of the Monitor 40's I can only truly speak on their behalf...

I am really amazed by these speakers. I bought them originally for surrounds, now they serve as my mains in my HT room and they do admirably. For their price, they really aren't that bad and most people will knock them because they are Polk.