As part of the ranking system in Call of Duty: WWII, Divisions have their own, separate ranking system which provides additional gear, XP, and more.

Divisions also have their own Prestiges that you can go through, and prestiging divisions will provide unique rewards only available through prestiging a division. These include unique weapons (1 per each division), additional basic training selections, new uniforms, and more.

The message in-game says to “be sure to prestige all 5 Divisions.”