Yes, there is a big difference between they typical money player and the typical freeroll player.
First off, people tend to prefer playing
real money games, and real money games earn a good player a whole lot more $ per hour. So if a player is good there's no reason to sit around for hours trying to win a buck or two in a freeroll. This takes many of the good players from the freeroll pool.
Second there's there's little investment in the game, so people do not take it as seriously. Since it costs nothing to join, more people will have a "hope to get lucky" mentality and take unnecessary risks. Losing $0 is not an incentive to play a solid game.
Freerolls also tend to be bastions for new players (who don't have the experience/knowledge/
bankroll to play money games), or the people who don't take poker seriously enough to make any real investment (financial or learning) in the game.
So basically what it comes down to is, good players migrate over to money games and move up. Freerolls thus freerolls are left with the bottom of the barrel players. Yeah, some good players will hit freerolls, but *all* of the bad players hit them too, because you can't get any lower than free.