For questions relating to the physics and tactics surrounding combat outside all planetary atmosphere. This includes ship-to-surface, ship-to-ship, and personal combat (space walking). The tag is appropriate when asking about the consequences of tactics, technology, cheistry, and physics of weapons and defenses.
"Space warfare" describes questions that are asking about the process, procedures, and technolgies of combat outside of an atmosphere. This includes battles in orbit around any celestial body and in deep space.
These questions can be about ship-to-ship encounters, planetary bombardment or engagement, and combat involving extra-vehicular people (usually soldiers).
Most commonly these questions involve the weapons and defenses used during space combat, but ay also discuss issues of logistics, propulsion, engagement, etc.