The main difference is, that in tournaments your goal is to outlast other players, unless its a winner takes all format, or you are down to the final two. So there is a tactical element to tournaments, especially when you get near the money, or you are on the final table. In cash games on the other hand, a dollar won or lost is a dollar won or lost. So you are always playing in, what tournament players call chip EV with the caveat, that you need to take rake into account, if its a raked game.
In tournament stacks also tend to be shorter most of the time, which mean, you dont need as strong a hand to stack off, and less
hands make it to the turn and river. Of course all tournaments are not the same here. Some might only give you 10-25BB to begin with, while others give you 200BB or more. Some have a structure, where blinds go up very fast, and for others its much more slow.
These days a lot of tournaments also have bounties, which again add another element of strategy, because now you not only trying to outlast other players but also to knock them out. So tournaments are not just tournaments, like cash games are not just cash games. For new players I do think, its best to pick a path and focus on one or two formats. But with more experience it should be possible to beat both cash games and tournaments, at least in the micros and perhaps also low stakes.
