[daedalus_f]

I’ve heard that distinction used in the UK.

The other down side of buoyancy aids I was told about is that many (most?) will not turn you face up if you are unconscious. Gives useful extra mobility for sports but can be fatal if the wearer is unconscious.

[brazzy]

It depends on the design of the specific device. A buoyancy aid with a foam collar will do it, but is less comfortable to wear. With an inflatable life jacket, to collar is not noticeable until it inflates.