drainage well vs storm sewer

drainage well and storm sewer both are nouns.

Word	Noun	Adjective	Verb	Adverb
drainage well	Yes	No	No	No
storm sewer	Yes	No	No	No

As nouns, drainage well and storm sewer are synonyms defined as:

drainage well and storm sewer: a system of watercourses or drains for carrying off excess water

Other synonyms of drainage well include drain system, storm drain, stormwater drain.

drainage well (noun)	storm sewer (noun)
a system of watercourses or drains for carrying off excess water	a system of watercourses or drains for carrying off excess water