Skate is a hardcore simulator - totally physics-based and paying an impressive amount of attention to the feeling of real life skating.
Skate focuses on realism - you can't rush up a vertical ramp at full speed and suddenly grind at the top. The physics won't allow you to - you'll carry on up into the air. You can't leap to some ridiculous height and make your boarder do a silly number of tricks, kicking the board in a flurry of different directions. In Skate, you leap into the air, kicking your board in a direction to perform a stunt quickly before you land realistically.