Whats the Difference? Parallel and Grey Imports

Hello,

I have just bought a CX500C 1979, that was at one stage imported
(Though god knows where from... my guess is America?)

For insurance purposes, would it be a grey or parallel import?
My guess is that a parallel import is one that is identical to one
sold in the UK, just shipped over from somewhere else. Am I right?

Thanks, Owen