Under the marvel-comics tag I have seen many questions on earth-616. Are there any other versions of earth as well? How do they differ from each other?
There are many, many more - there is a list of them on the Marvel wikia.
The main ones are:
- Earth-616 - Main Marvel Universe
- Earth-1610 - Ultimate Marvel
- Earth-148611 - New Universe (Home reality of Justice, Nightmask, Star Brand and Spitfire and the Troubleshooters.)
- Earth-555 - newuniversal (reboot of the above)
- Earth-45828 - Razorline (Clive Barker's Razorline imprint)
- Earth-88194 - Shadowline (Home reality of Doctor Zero, Power Line, and St. George and origin of Terror)
- Earth-93060 - Ultraverse (Malibu Comics)
- Earth-818793 - Army of Darkness
- Earth-8311 - Larval Universe (spider-ham etc)
- Earth-928 - Marvel 2099
- Earth-295 - Age of Apocalypse
- Earth-982 - MC2
- Earth-92131 - Marvel Animated (X-Men: The Animated Series)
- Earth-199999 - Marvel Cinematic Universe (MCU)
- Earth-2149 - Marvel Zombies
More difference detail on wikipedia.