Earth is supposed to be largely modernized. Yes magic now exists there along with magical creatures, but they've only been around for the last 20 years aside from rare, rare exceptions.

Basically, if you put Earth as your world of choice, you should probably be human and have powers/abilities based mostly on technology and SCIENCE with a bit of magic on the side maybe. Alternatively you could be one of the few exceptions and use MAGIC and SCIENCE in equal quantities. From how Cynder described it, the situation is akin to Wizards and Muggles in Harry Potter, but with the gap being even larger. Wizards/Witches are basically non-existent in the day and age, but their numbers have probably grown in the last 20 years since Earth and Lucis touched. 

A mage from Earth is almost certainly going to be less capable than one from Lucis though, just because of the situation in the two worlds. Magic is highly secretive and restricted on one planet, while open and in constant development on the other. 

As for why there seems to be no distinction? I guess people don't bother reading through the Free OOC for small details like this not included in the OP.