Those weapons both do standard damage, along with some movement. I think probably (never tried it) if you target the planet, it will just do the standard damage.
Think of it like you are targeting the units, pop and facilities in the planet, and not the planet and it makes more sense. Pushing and pulling the units and facilities on the surface of the planet in relation to the planet itself.
"Helmsman, target those 4 million Xiati with our tractor beam. At 500 meters, let 'em go." 
Geo