Fedora releases every six months. RHEL has a major release every three years, with minor releases every six months.
The major release of RHEL is usually forked from a Fedora version about a year before the major release, so with some exceptions software versions tend to be about a year behind those in a Fedora release initially, and then as RH backports patches rather than revving versions, drifts further.
It's the patches and smaller updates — and new hardware enablement in the full-support phase — that will be landing in CentOS Stream. Previously, this stuff was developed internally and only released to the world at the minor-release drop every six months. Now, it'll be developed in a shared space. So what you'll have in CentOS Stream is whatever is intended to ship in a RHEL minor update within six months.
There may occasionally be a situation where an update introduces bugs into Stream that would have been caught by QA before a public minor RHEL release and subsequent CentOS Linux rebuild. But I don't actually expect that to happen enough to worry about in any case where you can justify not paying for actual supported RHEL in the first place.
The major release of RHEL is usually forked from a Fedora version about a year before the major release, so with some exceptions software versions tend to be about a year behind those in a Fedora release initially, and then as RH backports patches rather than revving versions, drifts further.
It's the patches and smaller updates — and new hardware enablement in the full-support phase — that will be landing in CentOS Stream. Previously, this stuff was developed internally and only released to the world at the minor-release drop every six months. Now, it'll be developed in a shared space. So what you'll have in CentOS Stream is whatever is intended to ship in a RHEL minor update within six months.
There may occasionally be a situation where an update introduces bugs into Stream that would have been caught by QA before a public minor RHEL release and subsequent CentOS Linux rebuild. But I don't actually expect that to happen enough to worry about in any case where you can justify not paying for actual supported RHEL in the first place.