The Two Races

Zenith:
The technologically advanced race. They lack the ability to directly interact with the elements but can use the technology they created to help them master these elements. Though they can never gain full control over the elements they can wield more than one at a time. Since it is the items or weapons that wield the power not they themselves. Some have gone as far as to replace body parts with mechanical parts , replacing an arm for a gun or a sword to be more effective in combat. However even still , direct control of the elements is impossible , the machine portions of them channeling the energy.

Xenith:
The magi are able to channel the energy directly through their bodies , creating the element they were born to use. However even though the can control , create and manipulate the element they can never learn to use another element or its abilities. They have to learn to work with what they are born with. Some people have been able to build up immunities to their own element while other have not. Although it does take great amount of training to become immune to your own element its impossible to become immune to other elements. Some elements of course are impossible to become immune to. And some immunities are unwanted , such as the water healing magic having no effect on you would be unwanted. Also there are tales of mages who are able to wrap their bodies in the element for battle , though these cases are rare and normally terrifyingly powerful.