Are Rock and rock and roll the same thing?

This guy was telling me that rock and rock and roll are different styles of music is this correct?|||Although Rock was originally just a shortened term for Rock N' Roll, they've come to mean different things. Rock N' Roll in the most strict sense would only refer to the 50's style of Rock, and in a more liberal sense anything that "Rocks". Motorhead is ******* Rock N' Roll but it wouldn't be Rock N' Roll in the sense of the 50's genre but it would be in how it Rocks.