I switched from Neovim to Helix as my primary editor for around a year before switching back to Neovim. The way I'd describe the difference is that Helix is a text/code editor and Neovim is a toolkit to build a text/code editor. Helix is very simple and hits the 'just works' pretty well, but it's development is slow and w/o extensions it isn't flexible enough to handle every situation. Neovim can be a PITA to setup and maintain, but it's flexibility and power are very compelling. It also is semi-mainstream and gets a lot more support... eg. it has the only official, non-vscode, copilot plugin. I still use Helix as my backup editor (when I'm fixing issue with Neovim) and I look forward to it maturing a bit more and for the extension system to land and see where it goes after that.