galene is a single GO-binary afaik. Jitsi needs and XMPP-server installed.
True. Galene is designed to encourage small deployments: it's a single binary that is simple enough and cheap enough so that every high school can have their own instance and not rely on an external IT team.
For large deployments, where accidental complexity is not as much of an issue, you'd most probably want to use some more complex and more flexible software.
So probably a play on the name of the parent project.