I am not sure why. Maybe I change shoe sizes to achieve the level of comfort for my feet with every different style. My Nike rubber shoes are size 9. They are very comfortable for jogging. My black grendha flats are size 38 while my gold grendha pumps are size 37. When I bought those gold grendha pumps, I initially asked the salesperson for size 38 but when I tried it, the pair was very loose, they would literally fall off when I walk. I asked for the smaller size, instead.
My closed office shoes are size 4, kids size. =) My open toe pumps are generally size 8. Other fashion shoes are size 9.
|Shoe size conversion chart was taken from Voodoo-Dolly.com|