"An area in the north"
Translation:Ett område i norr
They're essentially synonymous, but they're used somewhat differently. We tend to use område in a more general sense, and region for an area within which things have something in common - like a political administration, cultural bonds, similar natural environments, etc.
I posted a table recently in another thread: https://forum.duolingo.com/comment/23446174/My-cousins-live-in-eastern-Russia