Your question is whether freerolls are tougher or not then buy in MTTs and the answer is NO, they are not.
It is the most standard abc poker that you need to be able to usually get to the money. However, the variance is indeed quite higher then in buy in MTTs, but the play itself is far easier.
As an example: there are these 5000$ freerolls on PS (turbo tournaments), if you play for money, sometimes those chest that we open give you a ticket. Today I played it for the first time (who knows how many times my tickets expired before), and I was surprised at how easy the tournament was. It was indeed a standard shove mania just like in any freeroll. The only thing I did was tighten up, didn't play anything fancy, just standard poker, and it got me all the way to 200th place out of 25000 players total.
Therefore, to play in freerolls is very easy, standard poker, tighten your range, make 30-50% pot sized c-bets, re-raise only when you have something strong on the flop, call with draws if u must but do not re-raise all to preserve chips...
The bad players will always find a "reason" to call you with weaker holdings.
As oppose to all that, in regular tournaments players are generally mindful of the game, paying attention to details, table behavior, hand history which makes it harder to play. That means, you need to make good quality decisions, you will be in tough spots more often then in freerolls etc.
To sum it up:
The gameplay in freerolls is easier in terms of opponents skills and decision making, but it is harder to actually get in the money in freerolls, because of the varience..