No, in regards to the two different ways to make a fist.
If I put my fingers into the center of my palm (basically following the Head Line in palmistry) and then tighten my hand around it to make a fist, it puts my pinky further back from the other fingers and makes a more angled punch. If I instead curl the fingers as tight as possible before curling them down onto my palm (where they rest over the Heart Line) then my knuckles are slightly straighter.
I think that nails affect this, as I think it's more comfortable to put longer nails into the crease of your hand than it is to dig your nails into the pad of your hand. Of course, we recommend students cut their nails anyway, so we don't scratch each other when we're practicing, and also so you don't have a nail bent back accidentally (I failed to follow this rule a month ago and ended up getting half my toenail ripped off when I performed a throw on someone else).