In cash games, you have to have a good solid strategy in how you want to play and other players really look at how many hands you play and how aggressive you are.
In tournaments and sngs, your strategy changes and most of it is because of stack sizes. Because of blinds increasing, you have to get real aggressive at time or start tightening up and avoid losing unnecessary chips.
Also, freeroll mtts and regular mtts are a lot different. In freeroll mtts, you have to be really tight and a lot of times just go all in with big hands because theres higher chances you will get called. Theres more donking going on and players are really just looking at increasing their own stack - they dont pay attention to how others are really playing. You will either get super tight or really loose players.