There's two types of armor in The Division 2: Brand, and Gear Sets. Brands are your generic armor types that still provide bonuses, with less intricate, or nuanced benefits. Gear Sets need to be worn in greater number (often above 3), and give much more detailed, niche bonuses that often relate to a specific playstyle. In most instances, players mix and match some (or most) of both.

Here's cheat-sheets for both. Enjoy!