The main difference between Brazilian and European Portuguese is the accent, Portuguese people push their words together and sound very nasal. In Brazil (in general) they speak a bit slower. It’s a bit hard to generalise Brazilian accents because they vary hugely. Brazilians also say that Portuguese is more flowery, and that they’re impossible to understand.
I learned European Portuguese, and I still have a sort of Portuguese accent I’m told (often laughingly). I haven’t had too many problems adapting, the mineiro accent is difficult whatever Portuguese you’ve learned, and I haven’t found much difference in words meanings, except for two notable occasions.
The first one was with the word for breakfast. In Portugal they call it pequeno almoço (literally small lunch, the same as French’s petit déjeuner), but here it’s café da manhã. My flatmate would always say that she was going to have café in the morning, but since she always did have coffee at breakfast I thought that was what she was referring to. I continued in my innocence for several weeks more until she walked into the kitchen and asked if I was having ‘café’, and I said no, it’s tea. She thought this was absolutely hilarious and had to explain that she meant café da manhã, or breakfast, causing me much embarrassment.
Secondly was a rather different situation. I went to Rio with two friends, and we were having lunch in Copacabana. We were at this small bar, and there was a sign advertising a promotion on ‘batidos’. We took this word at its European Portuguese meaning, a smoothie. It was a hot day, and we decided that a smoothie would be lush, so we ordered the passionfruit one. We had quite a shock when we tried it, because it was very alcoholic! We didn’t want to look like ignorant gringas, so we ordered a Sprite to dilute it, and drank it (it was nice, not going to lie). We later found out that batidos are always alcoholic. We had a lovely afternoon at the beach after our tipsy lunch!