Difference between factory and Tumbleweed

I doubt this is a good section for this thread. Some days ago OpenSuSE Team changes type of Factory repositories. I don’t know the difference between Tumbleweed and Factory.

Hm.
Probably Pre-Release/Beta would have been more appropriate?
Or maybe even Soapbox or General Chit-Chat?
As this is not really asking for technical help…

Some days ago OpenSuSE Team changes type of Factory repositories.

Not really.
What changed is that things are now getting more thoroughly tested before entering Factory. Especially there are integration tests in place, so that one package update does not break other packages e.g.
And the whole Factory is getting automatically tested as well all the time, e.g. if the installation/ugrade from an earlier openSUSE version works, if the system boots to the desktop, if there’s a network connection and so on.

Not Factory itself has changed much, but the development model, i.e. how packages end up there.

I don’t know the difference between Tumbleweed and Factory.

Well, I would put it this way:
Tumbleweed is an addon repo for the latest openSUSE release that adds the latest versions of selected packages.
Factory OTOH contains the latest versions of everything, and it is a “distribution” of its own. And it still is the place where the next openSUSE version gets developed, as it was in the past. (the next openSUSE is split off at some point of course and developed independently)