oilskin vs mackintosh

oilskin and mackintosh both are nouns.

Word	Noun	Adjective	Verb	Adverb
oilskin	Yes	No	No	No
mackintosh	Yes	No	No	No

As nouns, mackintosh is a hypernym of oilskin; that is, mackintosh is a word with a broader meaning than oilskin:

oilskin: a macintosh made from cotton fabric treated with oil and pigment to make it waterproof
mackintosh: a waterproof raincoat made of rubberized fabric

Other hypernyms of oilskin include mac, macintosh, mack.

oilskin (noun)	mackintosh (noun)
a macintosh made from cotton fabric treated with oil and pigment to make it waterproof	a lightweight waterproof (usually rubberized) fabric
	a waterproof raincoat made of rubberized fabric