@Neff grapes in France are called 'raisin', and plums in France are called 'prune' so I think there's your root - guessing they're Roman/Latin, and the English words were second?
@Neff @Zoonie Many of these things stem from the Norman Conquest, when the words for things changed if the new (French speaking) nobility used them, but not if they didn't.
For example, meat of cattle became beef from boeuf because the rich ate it, but the animal itself is a cow because the rich didn't farm.
@Zoonie hmmm interesting. Thanks!