What is the main difference between the two, besides price. Obviously there has to be something better about the Select, but what is it?

Supposed to be more uniform. I.ve tried both and there doesnt seem to any difference in preformace to me. And like ya said the price is a big difference.

The Select is run though a few more screen operations to make sure that all the size of grains are more uniform. The RS while uniform does not go the few extra steps. Is there a difference? They will have about the same velocity with the same projectile and rifle, they clean up about the same, but the price is the biggest difference. For many years all I ever shot was Select. I went to the shoot and was out of powder, so I went to the store and they were out of Select. So I bought the plain old RS. It shot the same. I never bought the Select after that time. I just could not justify the expense. Now some people claim it is a better powder and they get better accuracy.. OK, I am not going to argue with them. I just never saw it.

I've used them both. Can't say I see a difference.

Granuals are a lot more consistant. I tried a can of select and thats all i am using from now on in my sidelocks. Its a great powder. It only costs me $3 more than what RS costs.
Groups have also shrunk greatly in my fathers cabelas hawken.

The real differance is in the siffting the fine stuff that you fine in the bottom 1/4 of a can of RS is not in select to any extent unless the can has been beat around a lot.