5/8" MINUS GRAVEL
The mainstay of all driveways and parking pads, 5/8 "MINUS" means stones ground to 5/8" size - OR LESS - and the less part means it will pack together tightly and support significant weight.
5/8" CLEAN
5/8" Clean doesn't contain anything lower than 5/8" so it makes a very strong filler for drainage systems or other areas where minimal compaction is desired.