Is there a difference?
IMHO
Beatles, Stones, CCR = Rock n' Roll
AC/DC, Van Halen, Guns n' Roses = Rock
I agree. Bands like AC/DC. Van Halen, Guns n' Roses, Led Zeppelin, and others, are often categorized as Heavy Metal. But, I never thought of them as such. There like a step above rock n' roll. AC/DC and Zepellin are both heavily influenced by blues and early rock n' roll.