water parting vs watershed

water parting and watershed both are nouns.

Word	Noun	Adjective	Verb	Adverb
water parting	Yes	No	No	No
watershed	Yes	No	No	No

As nouns, water parting and watershed are synonyms defined as:

water parting and watershed: a ridge of land that separates two adjacent river systems

Other synonyms of water parting include divide.

water parting (noun)	watershed (noun)
a ridge of land that separates two adjacent river systems	an event marking a unique or important historical change of course or one on which important developments depend
	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