drainpipe vs sewer

drainpipe and sewer both are nouns.

Word	Noun	Adjective	Verb	Adverb
drainpipe	Yes	No	No	No
sewer	Yes	No	No	No

As nouns, sewer is a hyponym of drainpipe; that is, sewer is a word with a more specific, narrower meaning than drainpipe:

Other hyponyms of drainpipe include culvert, scupper, cloaca, sewerage, soil pipe, trap.

drainpipe (noun)	sewer (noun)
a pipe through which liquid is carried away	a waste pipe that carries away sewage or surface water
	misfortune resulting in lost effort or money
	someone who sews