Windows 7 comes in several different editions. The price is different for different sets of features. Windows 7 Home Premium is one of these editions.
Look here for a comparison of features for the editions "Home Premium", "Professional" and "Ultimate":
Personally I prefer Professional edition. It gets you that nice "Windows XP" Mode, which is basically a copy of XP that runs inside Win7 for programs that are do not want to run on Win7. The few features Ultimate gets you don't really seem worth it.
The second one is PREMIUM.
:O you don't say
Thank you :D