Assault vests and tactical webbing have been used by the military, law enforcement and private military contractors across the globe for over five decades - Whilst the gear has improved with new fittings and high tech materials the principles of carrying equipment has stayed the same.
What is a plate carrier? A plate carrier is a vest that is worn over the body and its primary role is to carry armour - This can be soft armour or harder steel, ceramic or dummy/training plates. The purpose of the plates and the carrier are to protect the vitals of the operator. Some plate carriers are designed just to carry plates where others are designed to also take molle attachments like pouches for magazines and other gear. Modular carriers can not only take accessories on the front of the carrier but also on its back. This is where a small modular pack can be attached for use with hydration or to carry items that might be needed in the field (Ammunition, Food, breaching chargers, cans of Monster?)
What is a chest rig? A chest rig is a piece of load-bearing equipment that is worn on the front of the body (on the chest). It can be fixed (all the pouches are stitched to the rig and can not be removed or moved) or modular (normally with molle webbing where pouches can be moved or removed depending on the role that the wearer is performing. Chest rigs differ from plate carriers as they are not designed to carry armour (soft or hard plates). Chest rigs are normally used in roles where the operator is based in the field and might need to carry a larger pack to sustain themselves or also in vehicle-based operations.