OK, simple, I have centre lock discs but because of the hubs (Red Metal) can only use the cheaper rotors with rivets close to the centre.
In six years I am on my second set of rotors.
I've used Shimano resin pads (OE - pretty rubbish), Shimano organic,Superstar sintered, carbon and organic, Ashima organic, Carboncycles sintered and organic (although I think they are the same as Superstar)
They have all worked perfectly well, and the rotors have coped with it all.
So no idea what the difference is but I'm happy to use them.