Ubuntu software center is a version customized by Canonical, and packaged as a Snap since several Ubuntu versions (currently 20.04 LTS and 21.10).
It is a front end to
apt-get, but at the same time also to
snap. Thus, it can install both traditional APT packages from official Ubuntu software sources and added PPA's alike, but also can install software from Snap, the new universal software packaging system of Canonical.
Snap software is designed to run on several linux distributions, and is updated regularly. APT software remains at the version of your Ubuntu distribution, except for security updates, and except for Firefox. That is why you see a newer version along with an older in the Software center. You see the Snap version and the APT version. With
apt get, you only have access to the APT version. Also there, you can have a newer version provided a PPA for that is available and enabled on your system