Sandisk Clip Jam

Why does the clip Jam get shorter battery life than the Clip Sport? Some have mentioned that both have a 220 mah battery and are built on the same platform. If anything, I would expect that the display on the Clip Sport uses more power than that of the Clip Jam… Perhaps the battery in the Jam isn’t 220 mah? i have seen photos of the Clip Sport disassembled, and the battery is in fact 220 mah. I haven’t seen photos of the Jam disassembled though.