Do a google image search on glamour and pin-ups and see if there's a general trend. Photography.com has a pretty good take on glamour:

When I think of pin-ups, I tend to think of the classic 40s-50s images like Bettie Page as pictured above. If there's any distinction, I'd say I think of pin-ups as being more 'cheeky', maybe with a bit of a funny story in the scene being acted out, often voyeuristic e.g. the model being caught with her skirt blown up by the wind etc. I think It's really rather arbitrary trying to separate the two though. While either one may incorporate nudity, I'd say it would be non-explicit, i.e. 'naughty bits' discretely covered. That would be like the so-called 'lad mags' of today like Maxim and FHM.

 

 

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