I’d say the biggest differences are:
(1) increasing blinds — which affects strategy and forces you to make moves that you don’t have that kind of pressure in cash games
(2) you don’t get to choose tables — so you need to learn to adapt
(3) because of (1) there are a lot more all-in moves especially as the blinds go up
(4) there is a bit of a shift in play the closer you get to the bubble — a lot of people tend to tighten up closer you get to the bubble... not necessarily the smarter move, but it happens a lot... and once bubble bursts, more wildness ensues.
(5) you have to budget more time to play a tournament if you plan to do well — microstakes tournaments can go as long as 6-8 hours. Or more. So endurance and staying mentally sharp over long periods becomes important
(6) mental game becomes important and being able to stay out of tilt during tournament is key if you want to do well
I’m sure I’m missing something. And by the way, I’m only talking about
online poker. There are prob many more differences live but I’ve very rarely played live so I can’t speak to that. Good luck!