I'm showing my ignorance here, and probably could find the answer if I looked (Googled) hard enough, but hoped maybe someone on here would explain in in SIMPLE enough terms that maybe I could understand it?

I would like to know what the difference is between these two - (CBOT) and (ACE) and why there is so much difference? Thanks, haven't paid much attention to markets til recently.

http://www.krvn.com/markets?page=corn

(Tue Mkt (Medium).JPG)

Tue Mkt (Medium).JPG (108KB - 373 downloads)