Free Market Vs. Open Market

I recently have been exposed to a software which helps businesses sell, service, track, and bill customer and affiliate accounts in the communications industry.  After some time with this, I began to wonder just how open a market we have here in the US.  Then realized I did not really know the meaning of many of the terms we use to describe our economy.

What is a free market?
What is an open market?
How do they play into capitalism?
Do we really operate openly or freely?

Following are some links to initial anecdotal information that might start the search:

Free Market vs. Open Market
Capitalism vs. Free Market

Popular definitions:
Open Market - Wiki Definition
Free Market - Wiki Definition