Difference between online and in person poker ?

I’ve been playing mostly online poker on Appeak poker app and have been winning most of the time.

I decided to try my hand at some low stakes game 1/3 100 dollar buy in in Vegas and I got wiped out twice lol.

Just wondering how different real life poker is vs online

Also, online I can only play 5 players max vs 8-9 in real life. Does that make a big difference ?