Bio means life or living Cell isn t mechanical or not completely mechanical Notice that he has living tissue example During the battle with Gohan he is blasted by an enormous Kamehameha Wave as a result he loses a few limbs and starts to BLEED MACHINES DON T BLEED This is proof that he is more than a simple Jinzoningen Also notice that 16 20 don t regenerate while cell is the only Jinzoningen that does besides Coola if he even counts