The main difference between cash and tournaments are stack sizes. With larger stack sizes come larger bets postflop.
In a tournament, you might bet 40% pot. In a cash game, you bet 80% pot. In a tournament, you are so short-stacked that you can go all-in with top pair. In a cash game, you'll go broke if you're constantly stacking off with TPTK and overpairs. In a tournament, there is very little implied odds
and chasing draws. In cash games, the whole game is about draws and protecting yourself with large value bets.
To be completely honest, 2NL cash games are a lot tougher than $1 SnG's. There are far less spewy fish in cash games compared to $0.50 SnG's and freeroll MTT's. You will struggle at first. But once you reach $5+ SnG's, you'll find tournaments and cash are both similar difficulty and it comes down to personal preference.