A Private Label marker is functionally the same as the base model, however brings its own unique milling and in some cases added accessories that can't be bought separately.
At the moment there are no PL Nerves in production. In the past the Nasty Nerve was available from paintballwholesalers.com and other retailers, however it has since been discontinued. The Nasty Nerve festured unique milling to the bolt knob, LPR endcap, body, backplate, and came with the Nasty trigger and vertical regulator milling from the Nasty Shocker series.
At the moment there aren't any plans for additional PL Nerves (nor are there any plans to resurrect the Nasty series).