All members of OnlyOuterSpace are most welcome to belong to both groups. The big difference is that ExoplanetsExomoons collects ONLY planets and moons from solar systems other than the solar system that Earth is in. So far I've formed only a few folders but I will be working hard to add more.
ExoplanetsExomoons collects all depictions of real or imaginary planets and moons, separated by the folders in the group to geologic type. Submissions may be digital, Filter-Forge-generated, traditional art, artisan craft objects including jewelry, cake icing, sculpture, polymer clay, so long as it depicts an exoplanet or moon. Photographs, if by some weird chance you have such, are welcome too.
Why not belong to both groups? Come and join!
Join requests are automatic. Submission to folders is also automatic, limited to 10 submissions a day.