MW versus MWh is one total capacity and the other maximum output?
MW is power, the rate of doing work. MWh is energy, how much total work can be done.

To use a water analogy, MWh is the size of the water tank, MW is the size of the pipe going to the tank.

Generally, larger tanks will have larger pipes, but that's not always the case. A small tank with a large pipe can fill and empty fast. This is what you get with high power LiPos, that fly drones for only 5 minutes. A big tank with a small pipe will take a long time to fill or empty.

If you want to shift a train to a platform, then you need a lot of power, high MW rating, but not for long, small MWh rating.