oiler vs supertanker

oiler and supertanker both are nouns.

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

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

oiler (noun)	supertanker (noun)
a cargo ship designed to carry crude oil in bulk	the largest class of oil tankers
a well that yields or has yielded oil
a worker who oils engines or machinery