how much difference between 3.91 and 4.10

I guess it is good to have alot to pick from. I myself have a set of 3.23's 2 sets of 3.55's all of witch are 741 cases. I have a 3.91 489 and a 4.10 742 case along with 3 clutch sure grips and a cone one. Everytime I find a good deal on a set I pick them up they are never going to get any cheaper.