I can no longer edit my original comment, so here is an update (new case and rearranging order) following suggestions by the other comments: A - Hobby project

I can no longer edit my original comment, so here is an update (new case and rearranging order) following suggestions by the other comments: A - Hobby project to play with some tech just because you find it interesting B - Hobby project to create something you want to exist (e.g. a tool for personal use or for close friends, an art project with interesting results) C - Hobby project to play with some tech that might help your career in the future by learning it D - Portfolio-making projects to show at job-interviews as a junior developer E - Homework project to learn about the tech you currently use at work F - For-profit project to hopefully earn some extra money on the side and keep it that way G - For-profit project to hopefully earn enough money that will allow you to quit your day job and make it your main job