When it comes to body armor, there are two main types. Soft Armor and hard body armor plates. Soft body armor is made from Aramid fibers, for example, Kevlar. These Aramid fibers are synthetically made and are extremely strong. Moreover, when they are tightly weaved, and stacked in multiple layers to support each other, their strength is increased significantly, and they can offer safety against pistol shots.
On the other hand, hard body armor plates are made from materials like steel and ceramics, most level III and level IV plates are made of these materials, whereas some new products are also made from UHMWPE. This super-lightweight material is only used to make NIJ level 3 and 3A armor, whereas some manufacturers also used it as a backing for level IV armor.
Level 3A armor is the only level that is available in both forms. You can also get bulletproof vests with level 3A body armor soft inserts, or you can opt for a UHMWPE level 3A plate.
As far as protection is concerned, it is important to comprehend that level 3A is a standard set by the NIJ, and both soft body armor and hard armor have to be tested and rated according to this standard. Therefore, an NIJ level 3A plate and soft body armor insert will offer the same level of protection.
Moreover, though armor plates are generally heavier than soft armor, a level 3A armor plate can be lighter. A typical level 3A bulletproof vest can weigh around 5-6 pounds, whereas level 3A plates, which are made of UHMWPE, can weigh about 1-1.5 pounds depending on the size of the plate. The AceLink Armor level IIIA plate weighs only 1.1 pounds, so with a front and backplate setup, you will still have more lightweight armor than a bulletproof vest. Additionally, a level 3A plate can ensure better multiple hit protection as well, however, they might not be as comfortable as soft body armor.