one is punomatic and one is hydromatic and that is all
hydraulic machines work with help of pressurised liquids where as pneumatic machines work with the help of pressurised gas
Any pressure difference is irrelevant. The distinction is in the operating fluid. In pneumatic systems, it's a gas. In hydraulic systems, it's a liquid.
In hydraulics. Power is transmitted through the air.The pneumatic. Power is transferred by the oil.
Hydraulics use liquids as the working fluid, pneumatics use gases as the working fluid.