They were created for recreational use. They are made with foam panels that keep you afloat. They are less bulky and more comfortable than lifejackets and come in many colours. Unfortunately, they have less flotation than lifejackets and are limited in their turning capabilities.
To wear a PFD properly, it needs to be done up reasonably tightly so that water doesn’t pass between your body and the PFD. Otherwise, you could slip out of the PFD.
Pros: less bulky and more comfortable than lifejackets, come in many colours. Cons: may not keep your face out of the water.