I dont think there is any difference in function, but the durability is ALOT lower than the Polycarbonate. I have no problems with BPA <- Stupid to say but, I dont! I would rather pay for durability once, than Tritan many times! I can tell the diference because if you hit the Tritan bottle, Flicking works... It sounds like a, soft plastic. The polycarbonate version sounds more solid.