oil tanker vs tanker

oil tanker and tanker both are nouns.

Word	Noun	Adjective	Verb	Adverb
oil tanker	Yes	No	No	No
tanker	Yes	No	No	No

As nouns, oil tanker and tanker are synonyms defined as:

Other synonyms of oil tanker include oiler, tank ship.

oil tanker (noun)	tanker (noun)
a cargo ship designed to carry crude oil in bulk	a cargo ship designed to carry crude oil in bulk
	a motor vehicle designed to carry liquefied loads, dry bulk cargo or gases on roads.
	a soldier who drives a tank