watershed vs geographical area

watershed and geographical area both are nouns.

Word	Noun	Adjective	Verb	Adverb
watershed	Yes	No	No	No
geographical area	Yes	No	No	No

As nouns, geographical area is a hypernym of watershed; that is, geographical area 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
geographical area: a demarcated area of the Earth

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

watershed (noun)	geographical area (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