drain system vs drainage well

drain system and drainage well both are nouns.

Word	Noun	Adjective	Verb	Adverb
drain system	Yes	No	No	No
drainage well	Yes	No	No	No

As nouns, drain system and drainage well are synonyms defined as:

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

Other synonyms of drain system include storm drain, storm sewer, stormwater drain.

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