What is the difference between Delta AcE Plus Gen.3 Winter Jacket and AcE Gen.2 Winter Combat Shirt?

Both products are intended for active use in extremely cold weather. However, one is a jacket with a full front zipper and the other is a combat shirt. Both are compatible with additional gear (i.e. plate carriers and backpacks). One of the many big advantages of the AcE Gen.2 Winter Combat Shirt is its exceptional comfort, while that of the Delta AcE Plus Gen.3 Winter Jacket is its extreme ease of putting on and taking off (credit for that goes to its long zipper).