As defined in the Cast Boolits website (www.castboolits.gunloads.com
) , "Boolits= as God laid it into the soil,,grand old Galena, The Silver Stream graciously hand poured into molds for our consumption. . . Bullets= Machine made utilizing Full Length Gas Checks as to provide projectiles for the masses."
Basically, it differentiates between the jacketed projectiles and the naked ones.