I used to use LXC maybe 5 years ago but I’ve since replaced everything with docker/compose. The main difference between LXC and Docker is that LXC is meant to be more like a Virtual Machine than a container. LXC containers run their own instance of systemd and can run multiple processes easily. Docker is meant to run a single process although people sometimes do hacks with supervisord or s6 overlay to run multiple processes.
At the time LXC didn’t really have a concept of images like Docker, it was just base images like Ubuntu 18.04 or Debian 9 and you’d shell in the container and install your stuff.
LXD is a tool built on top of LXC, confusingly enough the LXD client is called lxc… It’s higher level and might have the ability to use images, not sure, I never felt the need to learn it.