Once registered, you can download the 7.9 ISO through the standard portal or the developer's download page . ISO Specifications & Verification : rhel-server-7.9-x86_64-dvd.iso File Size : ~7.9 GB
Both are bug-for-bug compatible with RHEL 7.9. Their 7.x versions use the same source code (without Red Hat trademarks).
Are you planning to or use it for an in-place upgrade to a newer version?
: Use tools like Rufus (Windows), Etcher (Cross-platform), or the dd command in Linux to create a bootable USB.