I finally figured out the difference between the two. It’s simpler than I thought.
Both mean the same but あんまりis more used in informal speech. I miss such things tought in grammar because Japanese learners learn all the politeness levels but what about informal language?
When chatting with Japanese I was told “it’s ok to use informal language now” but I still used formal because I DON’T know informal word endings. I wish textbooks taught that.