1. The stakes. Play poker online with or without chips: you can choose the table you want. The variations of are impressive, which gives you the privilege of playing with whatever amounts you prefer. Texas Hold`Em: the bets are much higher. As you join the game, you have to accept the rules of a given table. If you cant afford yourself to spend much, you wont be able to play for a long time.
2. The atmosphere.
Online poker: while playing online, you only get the chance to stare at your screen. Unfortunately, there is no way to see opponents face and scan him.