Well, for starters:

On Earth, only 7% of the population is a mixture of "mythical creatures". Up until twenty years ago, they only existed as myths or stories. People had seen sightings of them, but nobody truly believed until the gateway to Lucis was opened; both creatures and their hunters came forth. Because of disbelief and general fear of them, creatures have been treated with a sense of injustice and subjected to heavy racism. Despite this, many have helped Earth for the better.

On Lucis, humans make up about 15% of the world's population. They've been considered the "weaker" or "lesser" race for many years, due to their limitations in terms of magic. That leaves the other 85% to be a mixture of mythical creatures. Nations ruled by humans are more likely to be attacked or conquered, but they aren't in danger or face much discrimination. In fact, more creatures discriminate against other creatures (namely Witches, Cursed Humans, Werewolves, Vampires, etc) that are seen as "dangerous".

Magic exists oi both worlds, however, Magic is close to obsolete on Earth. It has disappeared over time due to persecution and the bloody binds that history has on it -- in short, magic has disappeared in the Human race almost completely (aside from an "elite few" such as Pagans, modern day Witches/Wizards and the academies they may attend, etc). Magic is common in Lucis, however, it is more likely to appear in Creatures than in Humans. At the very beginning, magic had to be conjured through tomes, but has now evolved to be casted through incantations (some, however, still use tomes). Magic has several forms: black, holy, light, elemental, summoning and so on. Magic appears in runes, rune stones, mana, chi and so on.

Lucis has just begun to learn about advanced technologies. They have begun to learn the ways of advanced medication, warfare, electronics and so on. A normal Lucisean is far from versed in any field of technology aside from maybe a gun or rune-powered airship. While Earth has light sabers, laser pistols and so on. Earth has even begun an android program in the past couple of years -- Earth is far more technologically superior to Lucis.

Hope that helps.