retention basin vs river basin

retention basin and river basin both are nouns.

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

As nouns, river basin is a hypernym of retention basin; that is, river basin is a word with a broader meaning than retention basin:

retention basin: a storage site similar to a detention basin but the water in storage is permanently obstructed from flowing downstream
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 hypernyms of retention basin include basin, catchment area, catchment basin, drainage area, drainage basin, watershed.

retention basin (noun)	river basin (noun)
a storage site similar to a detention basin but the water in storage is permanently obstructed from flowing downstream	the entire geographical area drained by a river and its tributaries; an area characterized by all runoff being conveyed to the same outlet