- soulseek is the sharing platform (not sure how it works exactly, some kind of federation with a central broker to search for users? Like how Matrix by default uses the primary domain for 'discovery')
- soulseekqt is the program that enables you to interact with the soulseek network
- slskd is a program specifically for remote running soulseekqt on a headless (no display) server, and serves a web UI with separate login so you can access it from another machine
The use case for slskd is if you want your music to live on a different machine, whereas soulseek/qt is for if you want your music on your primary machine. Another reason I keep it on a server is efficiency - I can expose my collection for sharing without having my 200W+ PC on, instead my server takes ~60W, ~20 if i remove the GPU