The core distinction lies in the fundamentally different objectives of fiber selection and composite structural design. Protective composites prioritize "impact resistance and penetration prevention," primarily selecting high-strength, high-toughness fibers such as aramid or ultra-high molecular weight polyethylene. These fibers absorb energy upon impact and prevent projectile penetration. In contrast, 3D composites focus on "integral molding of complex structures," offering greater flexibility in fiber selection. Materials like carbon fiber or fiberglass can be chosen based on specific needs, with the emphasis not on extreme strength but on compatibility with 3D molding processes.