Astronomical Art is usually defined by its exponents as depicting 'pure' scenes in space or on other worlds; ie. landscapes, stars, planets, nebulae and galaxies as they would appear if we were out there looking at them with our own eyes.
Space Art can include all of these, but will include vehicles and hardware; spacecraft, probes, rovers, astronauts, bases, maybe even robots. . . This section concentrates on these. The 4th column also includes diagrams and cutaways, which can also be found in their own categories (eg. Volcanoes).