oiler vs tank ship

oiler and tank ship both are nouns.

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

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

Other synonyms of oiler include oil tanker, tanker.

oiler (noun)	tank ship (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