From Eden Eternal Wiki
The kind of armor you can equip is determined by which class you currently are, but you also have space for a set of each in your character equipment window.
There are three kinds of armor: Cloth Armor which is for Magic DMGers and Healers (excluding bards). It tends to have the weakest defence out of the three armor types.
Heavy Armor is for Defense classes. It generally has the highest defense out of the armors.
Most armor gives additional attributes, besides defence.