Protective gear consists of class-specific or general use outfits. Specific items provide various bonuses and protection against certain sources and types of damage.
Vests
Those protect most of your soldier's body and often confer bonuses to the maximum amount of carried ammo or protection against a specific type of incoming damage. Some can even restore your armor or enable you to survive being shot by a sniper!
Helmets
They protect your soldier's head from minor damage on longer distances; keep in mind that getting shot in the head will almost always mean dying. Some helmets protect against the effects of flashbang grenades and some might even restore your health or let you detect enemy mines from afar.
Gloves
Those provide some protection for your soldier's hands, but most importantly they often confer useful bonuses, such us increased reloading speeds of firearms or increased damage and attack speed with melee weapons.
Boots
Provides some protection for your soldier's feet and often provides varying bonuses to sprint length, reduced noise while running and sometimes even limited protection against mines.