For FDM 3D printing, PLA is a durable and reasonably priced workhorse filament. However, other material developers assert that adding chemicals to PLA filament improved it, resulting in PLA+, an improved form of the substance.
The PLA + doesn't have a single formula. Manufacturers can source formulas and combinations or create their own. Most of the time, manufacturers are secretive about their formulae. But if you look hard enough, you can find a few things.
Because PLA plus should be less brittle and absorb less moisture than regular PLA, it may contain a trace of TPU.