river basin vs catchment basin

river basin and catchment basin both are nouns.

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

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

river basin and catchment 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 river basin include basin, catchment area, drainage area, drainage basin, watershed.

river basin (noun)	catchment 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