acid rock vs rock 'n' roll

acid rock and rock 'n' roll both are nouns.

Word	Noun	Adjective	Verb	Adverb
acid rock	Yes	No	No	No
rock 'n' roll	Yes	No	No	No

As nouns, rock 'n' roll is a hypernym of acid rock; that is, rock 'n' roll is a word with a broader meaning than acid rock:

acid rock: a musical style that emerged in the 1960s; rock music inspired by or related to drug-induced experience
rock 'n' roll: a genre of popular music originating in the 1950s; a blend of black rhythm-and-blues with white country-and-western

Other hypernyms of acid rock include rock-and-roll, rock'n'roll, rock, rock and roll, rock music.

acid rock (noun)	rock 'n' roll (noun)
a musical style that emerged in the 1960s; rock music inspired by or related to drug-induced experience	a genre of popular music originating in the 1950s; a blend of black rhythm-and-blues with white country-and-western