abstract art vs op art

abstract art and op art both are nouns.

Word	Noun	Adjective	Verb	Adverb
abstract art	Yes	No	No	No
op art	Yes	No	No	No

As nouns, op art is a hyponym of abstract art; that is, op art is a word with a more specific, narrower meaning than abstract art:

abstract art: an abstract genre of art; artistic content depends on internal form rather than pictorial representation
op art: a style of abstractionism popular in the 1960s; produces dramatic visual effects with colors and contrasts that are difficult for the eye to resolve

Other hyponyms of abstract art include Art Informel, Informel, drip painting.

abstract art (noun)	op art (noun)
an abstract genre of art; artistic content depends on internal form rather than pictorial representation	a style of abstractionism popular in the 1960s; produces dramatic visual effects with colors and contrasts that are difficult for the eye to resolve