As far as how the game is played online in comparison to how it is played in real life, there are some differences. One such difference is that the players are no longer able to see the faces and body language of their opponents. Because of this, one is forced to pay more attention to betting patterns and other non-physical behaviors. Another difference is that the games can progress at a faster pace than in real life -- no longer is time wasted as the dealer collects, shuffles, cuts and then re-deals the cards. Nor is time wasted while players banter back and forth between themselves. A third difference is that online players are able to play multiple games at once which was not practicle in the real world. Is this is made possible by opening several poker games in several computer windows.
Because of the 24 hour a day availability of online poker, some people have dropped their "9 to 5" jobs and taken up poker as a source of income. These people will win themselves $80 or more after two or three hours of game time, and then have the rest of the day "off." Earnings of $80 a day would give the player around $2400 a month, and -- of course -- more earnings would yield a higher monthly income. For the devoted poker player, earning a living income off of what they enjoy doing would be a dream come true.
Your poker face? You don't need one while your playing online. And for some people that's a real advantage. However you'll have to still play each hand just like the hand you played before. If you bet $1 when you had a bad hand, someone might get suspicious if you suddenly decided to bet $8 now that you have a definate winning hand.
With all the poker games available online, why would someone go back to the real world and play? There are many reason, and for each person there is a unique reason so we could not possibly list them all here.