rock'n'roll vs rock music

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

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

As nouns, rock'n'roll and rock music are synonyms defined as:

rock'n'roll and rock music: a genre of popular music originating in the 1950s; a blend of black rhythm-and-blues with white country-and-western

Other synonyms of rock'n'roll include rock-and-roll, rock 'n' roll, rock, rock and roll.

rock'n'roll (noun)	rock music (noun)
a genre of popular music originating in the 1950s; a blend of black rhythm-and-blues with white country-and-western	a genre of popular music originating in the 1950s; a blend of black rhythm-and-blues with white country-and-western