Huge diffrence, lot looser and lot more agressive, be ready for huge variance, I played at pokerroom and was a big loser for months there before I began to master the game. I got sick of getting 3 bet all the time but its diffrent from site to site. Mansion is much softer I think. I dont play at pokerroom anymore at all, that place got rigged decks and the most amazing situations you get in compared to bodog and mansion. Im done with that site after 2 years of playing there after I noticed strange things there and that I actually could be on a bad streak on only that place and not all others losing every hand I played if I didnt have the nuts.