I feel like "Leela" is getting used to refer to both Leela and to Leela Zero lately here on the forums, and it means that I'm never 100% sure what people are talking about.
Leela: based on original AlphaGo technology from 2016 (training started by mimicking human games), comes with an UI, latest release Oct 2017, strong dan level.
Leela Zero: based on AlphaGo Zero technology (training is entirely through self-play), started training in late 2017, pro+ level.
Lizzie: GUI for using Leela Zero.
If I had my way, we'd stop saying just "Leela" (because I always wonder Leela Zero is really meant), and call the first one "Leela 0.11" and the second one "Leela Zero" or "LZ".
This is all Gian-Carlo Pascutto's fault for choosing such similar names, although ultimately I guess it is DeepMind's fault for setting a bad example.