720 and 1080 is how the picture is displayed. The higher the number the better the picture. Most people will not notice the difference if you are watching regular TV or DVDs. It makes a small difference when playing Video Games but not $100 worth. I would recommend 1080 if it is $50 or less than the 720 (ex:720 is $150 but 1080 is $200) I would get the 1080.
But if the 720 is $150 and the 1080 is $250, I would get the 720.
Hope this HELPS,