Hacker, well said
There are lots of little differences, and I was not shy about telling the first few captains I flew the line with that I'm new to the industry and am still learning the culture, techniques, contract, etc, that aren't taught in training.
Timbo,
My first go around in the sim I rushed to get the gear up right away (after positive rate) because in a T-38 if you don't do that, you will overspeed them...in an Airbus...not so much. My first engine fire in the sim, I too was leaning too far forward. Lesson learned on both accounts and it only took messing up once to learn it.
Some of the biggest challenges were on the ground...ramp control? EDTC's? I had no clue about that stuff.