dnf
yumとの違い
python 2→Python 3
yumはPython 2でしか動かない
しかしPython2は2020年にサポート終了している
RHEL8以降はyumを使うと内部的にdnfを使ったことになる In Red Hat Enterprise Linux 9, software installation is ensured by DNF. Red Hat continues to support the usage of the yum term for consistency with previous major versions of RHEL. If you type dnf instead of yum, the command works as expected because both are aliases for compatibility.
Although RHEL 8 and RHEL 9 are based on DNF, they are compatible with YUM used in RHEL 7.