surf music vs rock'n'roll

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

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

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

surf music: a genre of popular music associated with surf culture, particularly as found in Orange County and other areas of Southern California.
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 surf music include rock-and-roll, rock 'n' roll, rock, rock and roll, rock music.

surf music (noun)	rock'n'roll (noun)
a genre of popular music associated with surf culture, particularly as found in Orange County and other areas of Southern California.	a genre of popular music originating in the 1950s; a blend of black rhythm-and-blues with white country-and-western