apt-get, the modern apt command, aptitude... yum, dnf... The package registries also have multiple. Sticking with apt repos, Ubuntu has one per release, Debia

apt-get, the modern apt command, aptitude... yum, dnf... The package registries also have multiple. Sticking with apt repos, Ubuntu has one per release, Debian has one per release, Mint has one per release... So it's an n:n situation.