beat music vs rock-and-roll

beat music and rock-and-roll both are nouns.

Word	Noun	Adjective	Verb	Adverb
beat music	Yes	No	No	No
rock-and-roll	Yes	No	No	No

As nouns, rock-and-roll is a hypernym of beat music; that is, rock-and-roll is a word with a broader meaning than beat music:

beat music: a pop and rock music genre that developed in the United Kingdom in the early 1960s.
rock-and-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 beat music include rock'n'roll, rock 'n' roll, rock, rock and roll, rock music.

beat music (noun)	rock-and-roll (noun)
a pop and rock music genre that developed in the United Kingdom in the early 1960s.	a genre of popular music originating in the 1950s; a blend of black rhythm-and-blues with white country-and-western