Can someone please explain the different ball surfaces to me?

I understand that a polished ball will likely go longer then a unpolished. But how does the different grit types work? The lower the grit the more friction which in return is better for oilier lanes?

How come some balls can have a 4000-Grit finish polished or unpolished and made for medium oil volume while some balls are 1500-Grit polished or un-polished and made for lighter oil volumes?

The reason im asking is because is just got a pba magazine in the mail and it lists all the balls from 2007. It has for example a Columbia Wraith SF which has a 2000-grit polish for the box finish but its use is for light to medium oil, while you have a Black Widow pearl with a 4000-grit polish box finish but its main use is for medium oil conditions?

Im just trying to clear up a few things, thanks