tanker vs oiler

tanker and oiler both are nouns.

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

As nouns, tanker and oiler are synonyms defined as:

Other synonyms of tanker include oil tanker, tank ship.

tanker (noun)	oiler (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 well that yields or has yielded oil
a soldier who drives a tank	a worker who oils engines or machinery