They spec 2 different greases due to the difference in loads/heat at the contact points.
Gear to gear has a large contact area to disperse the load and heat generated. The pins that the gears spin on have very little mass, and tend to heat up more. The pins need a high temp / high speed grease, these small planet gears spin very fast.
The frequent interval for greasing is because you can only get a very small amount of actual grease on each point, so it doesn't last very long.

Climb fast, soar long!