Heavy metal and Rock 'n' roll

Heavy metal noun - Loud and harsh sounding rock music with a strong beat; lyrics usually involve violent or fantastic imagery.

Rock 'n' roll and heavy metal are semantically related. In some cases you can use "Rock 'n' roll" instead a noun phrase "Heavy metal".

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

Heavy metal and rock 'n' roll are semantically related. Sometimes you can replace phrase "Heavy metal" with "Rock 'n' roll", this phrases are similar.