tank ship vs oiler

tank ship and oiler both are nouns.

Word	Noun	Adjective	Verb	Adverb
tank ship	Yes	No	No	No
oiler	Yes	No	No	No

As nouns, tank ship and oiler are synonyms defined as:

Other synonyms of tank ship include oil tanker, tanker.

tank ship (noun)	oiler (noun)
a cargo ship designed to carry crude oil in bulk	a cargo ship designed to carry crude oil in bulk
	a well that yields or has yielded oil
	a worker who oils engines or machinery