Repos naming convention

Would anyone explain what is the difference and the purpose in the naming convention at the download.opensuse.org/repositories, please?
I am confused by the existence of similar repos with the same name and difference in the name by ‘:’. In addition content seems to differ (slightly) too.
I mean repos named like Virtualization vs Virtualization:, Emulators vs Emulators:, wine vs wine:, hardware vs hardware:, etc.

This post should be made to the “Install” forum, not the Virtualization forum (may be moved).

Personally,
Over the years I haven’t noticed a consistent reason, so when I’m browsing repositories I check them all out.

TSU

Moving to Install/Boot/Login forum.

Moved from the Virtualization forum and open for posting again.