Hope this helps -deep breath-
Moon crabs & halloween crabs-
Gecarcinus quadratus:
Though there may be more (sub)species, for the sake of care they're all the same. Originates from South American beaches. Primarily a land crab, their care is pretty much the same as hermit crabs. Meaning lots of land, humidity, fresh and salt water.
Vampire crab-
Geosesarma sp.:
A primarily terrestrial crab as well, but smaller than the moon crab. These prefer closer to 1/3 water, 2/3 land. Could be harder to locate. They are freshwater but
need hard, alkaline water. These crabs come from the island of Sulawesi, where many oceanic animals have adapted to living in the high pH (8ish) freshwater systems there.
Panther crab-
Parathelphusa panthernia:
This is another freshwater crab from Sulawesi (again will require the pH 8 water). However this one is fully aquatic (though they appreciate having a raft to climb onto every now and then). I've seen people keep them in fish tanks, but crabs will be crabs and causalities are possible.
The photos should help, people LOVE making up names and such for these animals, which can be confusing. 10 gallons is quite small for crabs, they like colonies to live in (at least 3 is a good starting point). All crabs are omnivores that love a mixed diet. The crabs on land appreciate a heat lamp and to be slightly above room temperature (22-26C in general off the top my head).
Some other crabs to look into are fiddlers (brackish water), red clawed crabs (brackish water) and hermit crabs (salt/fresh). These are the three most common crabs seen in stores generally.