LoL, my bad. How embarrassing. You do still get water.

But the point is, now that that one is used, that you do get less energy out through the conventional combustion than in fuel cells, even if both are technically oxidising the hydrogen in close to the same way.
This is because in the fuel cell engine, the energy is produced directly as electricity, and does not loose energy to heat, friction, etc before it reaches the electromagnetic engine (which doesn't count, since the energy has by that point left the engine).

Now don't you dare disprove that, or I'll have to flee in shame...