There could still be a slight difference. Spaceflight, arguably, includes flying through space through means other than a spaceship, such as by spaceborne lifeforms. Spaceships, as a tag, could include discussion of things that spacecraft can do or that can happen to spacecraft when they are not traveling in space, such as how long a spaceship of a specific type could survive on the surface of a specific type of planet with a hostile environment (e.g. highly corrosive).
In response to Nex Terren's comment, there could still be a substantial difference. Spaceflight, as a tag, could specialize in discussion of the mechanics of flight while Spaceships could specialize in issues of spacecraft construction, combat, repair, or systems.
For example:
"What would a trip to Jupiter feel like?" might be a good question for Spaceflight.
"A 4-person spacecraft crashes onto a 50 km radius asteroid with no atmosphere. How likely would it be that the crew would survive?" might be a good question for Spaceships.