Forget the differences between BrE and AmE. How about the differences between different parts of the U.S.? Like "soda vs pop" or "sneakers vs tennis shoes" or "lollipop vs sucker."
Here's a fun article with 10 of them: https://www.goodhousekeeping.com/life/a20898181/regional-dialect-words-vocabulary/
btw, Merriam-Webster added over 1,000 new words. "Welp" is now a word.
First Known Use of welp - 1994
Definition = used informally like well (as to introduce a remark expressing resignation or disappointment)