Wait what ?
I thought that bpj carries level 2 and 3a armor and is meant to protect against handguns while plate carriers insert level 3 or 4 plates which save you from rifle rounds.
Can you please confirm your claim?
Okay, let me explain.
BPJ is a misnomer. Nothing is bullet proof, it is just bullet resistant.
When we look at what is called a BPJ, it is just many layers of kevlar that provides good overall protection against handgun bullets and shrapnel. It also has a "pocket" in the front and back for inserting a plate, which makes it resistant to rifle rounds.
(note the good amount of kevlar packing around neck, groin and shoulders - Very good shrapnel resistance.)
A plate carrier is basically only the "pocket", where you can slide in the plates and have protection from rifle rounds. However, it wont protect you from shrapnel anywhere else apart from chest and back.