mackintosh vs oilskin

mackintosh and oilskin both are nouns.

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

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

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

Other hyponyms of mackintosh include slicker.

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