'A common people, divided by a common language...' (to paraphrase W. Churchill, quite possibly quoting someone else)
I noticed this in Japan when I was there on the JET Programme. I had fewer misunderstandings with Japanese people because when I didn't know what they were saying, I asked. I am from Ireland. I thought that I understood what Americans meant when they spoke. It turns out that I just knew the words and some of them had other meanings.
The only one that I really remember is 'to be done with' means to be finished. I was confused when I was if I was done with that. But then, the verb 'to do' does a lot of heavy lifting in the various flavours of English. Which, thanks to Microsoft & Apple, are disappearing.