Good question. As far as I can tell there is no real difference. Bushmaster had it first then got bought out by Remington (Cerberus) and now Remington has it. You will not see Bushmaster adds anyymore for the ACR, but instead you will see Remington adds. I could be wrong, but I think Remington is going for some kind of Mil contract and wants to use the ACR and their new sniper rifle.