when i think Pin ups, I think the archytypical Farar Fawcett poster or the Dallas Cowboys Cheerleaders posters that were on every teen boys bedroom wall in the 70's.

Glamour I see as the Dior, Channel, airbrushed, filtered, more emphasis on make up and skin tones.

Realism (to me anyway) is what the other two categories don't cover, eg, the athlete catching breath after a 200m sprint, the mother shedding tears over her sons headstone.

That's just my take on it........