I cannot see any real differnece. I know what you mean, however, about the difference. Most people nowadays in dressage ride wtih their stirrups too long. it's some kind of a fad, and people think they will have a better seat. But often they end up "fishing" for the stirrup and riding on their pubic bone too much and posting entirely off the knee.
When I ride Zulu, i have to keep the stirrup a tad shorter than optimal, becaseu I need to have a bit more connection t the stirrup in order to be albe to rise up over him, his trot is big and often not very steady.
But, if it's making your leg hurt, then maybe you'll have to let it go.
I did put some pads on my stirrups last year because the bottom of my foot was going to sleep, and this is almost like having a half hole raised. However, I wonder how safe this is and if it might not lead to my foot getting caught. The pads are just velcroed on, so theoretically, if I was caught and drug, they woudl come off.
(I hate to even imagine that)