Dumb question - EXIF info (f Stop and Aperture)

OK, here goes make an idiot of myself but always pleased to learn something....

In looking for inspiration in the gallery shoots and reading the EXIF data what is the difference between 'F Stop' and 'Aperture' aren't they the same thing (but they appear as different values in most EXIF data.

As I expect, a dumb question but please enlighten me..(excuse the pun!)

In the context of the Gallery Images, it is the 'F Stop' value that shows the aperture actually used to take the shot. I don't know what the 'Aperture' value shows as it seems inconsistent and I just ignore it. I'm sure someone will be able to enlighten us...........

Regards
David

I think it's because the aperture value varies for an F stop as the focal length of a zoom lens changes.