EPEL <> CRB, it is the same?

So far I’ve nailed down this:
EPEL: Extra Packages for Enterprise Linux, for RHEL & Stream (and others)
EPEL-Next: Additional package for Stream (and other, i.e. not officially for RHEL)
CRB: CodeReady Linux Builder repo

Is it the same?
Are all EPEL & EPEL-Next packages in the CRB repo?
Does CRB contain more than EPEL & EPEL-Nextpackages?

Why not a EPEL and EPEL-Next repo?

I found this EPEL description but it doesn’t say much about CRB: Extra Packages for Enterprise Linux (EPEL) :: Fedora Docs

I now see there actually is an epel and extras-common repo, maybe I don’t need to add the crbrepo with as described at docs.fedoraproject.org
dnf config-manager --set-enabled crb
dnf install epel-release epel-next-release

EPEL: community-maintained repo (sponsored by Fedora Project)
CRB: available with all Red Hat Enterprise Linux subscriptions (see here).

Yes, you enable crb first, before adding EPEL to your EL.

I still dont’ get the relation between CRB and EPEL/EPEL-NEXT?
Why not just add the epel repo for example.

And the packages epel-next-release & epel-release are located in the extras-common repo, not CRB repo (that would have made sense why you have to add the CRB repo)

EPEL and CRB are maintained in separate ways. EPEL is maintained by the Fedora/EPEL community, and is additive to Red Hat Enterprise Linux. CRB is part of the Red Hat Enterprise Linux product and is maintained by Red Hat employees as part of that product. They cannot be combined.

But why do you need to subscribe to CRB to get EPEL/EPEL-NEXT?

Several of the packages in EPEL and EPEL-Next have runtime dependencies on packages found in CRB.

The CRB repo is built as an auxilliary repository for packages and software that are not going to get different levels of support than the Base and AppStream repositories. Packages in BaseOS/AppStream/CRB are built ‘together’ in whatever build system you are using (RHEL, Rocky, Alma, CentOS Stream).

The EPEL repository is built separately in a different build system by volunteers of the Fedora Project using the binaries from BaseOS/AppStream/CRB as either buildtime dependencies or runtime dependencies. Most of the time, CRB was only needed for building software, but various code also requires things in CRB for runtime usage. Because the Fedora EPEL build system is separate and fairly ‘simple’, packages built in it do not know which repository in EL was needed for the built package to work… it just knows it needs a specific package.