Aye it can be a bit confusing. Multilib builds are like TDM's cross version but with a different layout.
Automated builds are just buildbot builds of there versions.
Sezero etc. Are personal builds with fixes to some problems (or) general improvements to the standard distros.
For instance the ada build has been on the backburner for years because of problems building gnat on windows with mingw64. Turned out the fix was an old TDM patch
.