drainage basin vs river basin

drainage basin and river basin both are nouns.

Word	Noun	Adjective	Verb	Adverb
drainage basin	Yes	No	No	No
river basin	Yes	No	No	No

As nouns, drainage basin and river basin are synonyms defined as:

drainage basin and river basin: the entire geographical area drained by a river and its tributaries; an area characterized by all runoff being conveyed to the same outlet

Other synonyms of drainage basin include basin, catchment area, catchment basin, drainage area, watershed.

drainage basin (noun)	river basin (noun)
the entire geographical area drained by a river and its tributaries; an area characterized by all runoff being conveyed to the same outlet	the entire geographical area drained by a river and its tributaries; an area characterized by all runoff being conveyed to the same outlet