oiler vs gusher

oiler and gusher both are nouns.

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

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

oiler: a well that yields or has yielded oil
gusher: an oil well with a strong natural flow so that pumping is not necessary

Other hyponyms of oiler include spouter, stripper, stripper well, wildcat, wildcat well.

oiler (noun)	gusher (noun)
a cargo ship designed to carry crude oil in bulk	an oil well with a strong natural flow so that pumping is not necessary
a well that yields or has yielded oil
a worker who oils engines or machinery