Mitten gauntlets might remind you of your winter mittens. The wearer’s fingers are protected as a group behind a single set of wide plates that attach at the knuckle line, and extend to cover the fingertips.
Demi-gauntlets are like mitten gauntlets but offer little-to-no finger protection. Having the fingers covered will seriously reduce their use, which is acceptable if the wearer is grasping a sword. However, some soldiers need use of their fingers more than this, and thus a demi-gauntlet is preferred.
Finger gauntlets protect each finger individually which allow more use than mittens and more protection than a demi.