How does BusCtl compare to QDBus?

busctl is from systemd, whereas dbus-qt6 (and dbus) are from qt6-qttools. These are very different projects, yet these tools perform the same purpose. Considering that both are fundamentally necessary to have installed at the same time as a user of a SystemD-based Linux distribution (Fedora) and Qt-based DE (KDE Plasma), which should I utilise, and when? If an example is necessary, consider: 1. busctl --user call org.freedesktop.ScreenSaver /ScreenSaver org.freedesktop.ScreenSaver Lock 1. qdbus-qt6 org.freedesktop.ScreenSaver /ScreenSaver Lock