The 5+ produce 5 watts of power on a single panel while the 10+ produces 10 watts across a folding dual-panel design. The "+" represents power storage, meaning that the 5+ and 10+ both integrate on-board batteries so you can store your energy from the sun for when you need it (say you want to charge up your gear at the end of the day when the sun is down). All models come with the Optimal Sun System designed to make your orientation to the sun super simple and intuitive.
Both models have the same 3200 mAh 8 Wh, lithium-ion battery.