watershed vs geographic region

watershed and geographic region both are nouns.

Word	Noun	Adjective	Verb	Adverb
watershed	Yes	No	No	No
geographic region	Yes	No	No	No

As nouns, geographic region is a hypernym of watershed; that is, geographic region is a word with a broader meaning than watershed:

watershed: the entire geographical area drained by a river and its tributaries; an area characterized by all runoff being conveyed to the same outlet
geographic region: a demarcated area of the Earth

Other hypernyms of watershed include geographic area, geographical area, geographical region.

watershed (noun)	geographic region (noun)
an event marking a unique or important historical change of course or one on which important developments depend	a demarcated area of the Earth
a ridge of land that separates two adjacent river systems
the entire geographical area drained by a river and its tributaries; an area characterized by all runoff being conveyed to the same outlet