NeoPixel (adafruit) and Plecter Pixel (Plecter Labs, et al) are really just brand names. NeoPixel has become the "Kleenex" of addressable LEDs, and Plecter Pixel is really, in my opinion, the Plecter Labs implementation of this technology in their boards.
From the beginning I always called them Pixel Blades. I think that is the proper general term. It was great to see it gain popularity and move forward in LightsaberOS (now FX-SaberOS), then Teensy, NEC and finally Plecter. Since then a dozen or so other boards have become either broadly available or have a at least some kind of following. There were many ideas floating around on how to connect the blades before NEC and Plecter got in on the action. I don't claim to be the first, and my first pixel based saber was made almost 3 years ago (started working on it at the end of 2015) while Vaders Vault announced "Plecter Pixel" less than a year ago (2017 Nov 28). Andras (Protowerkstatt) posted a video in 2015 as well.
I honestly have no idea who was the first to come up with the PCB/pogo concept or who was the first to execute it, but it was an idea that existed before it was popularized. Those involved in the early experiments (and sharing their information) tried dozens of different connectors, some ill advised, including anything from audio jacks (which was the original connector suggested in the PL manuals) to network jacks. Many of us settled early on aviation connectors or DIN plugs and continue to prefer them. Others prefer the PCB style and it's various implementations, others still use less appropriate connectors that aren't really designed to carry the current.