A package manager is a tool that allows users to install, remove, upgrade, configure, and manage software packages on an operating system.

The package manager can be a graphical application like a software center (or) a command line tool like apt-get.

Systemctl is used to examine and control the state of the “systemd” system and servicemanager. Systemd is a system and service manager for Unix-like operating systems (most distributions, but not all).

Systemd: Systemd is asuite of tools and libraries for managing system resources and processes in Linux-based operatingsystems. It replaced the traditional SysVinit system and offers a more robust and efficient way to manage services, devices, andother system components.

Systemctl: systemctl is the command-line tool used to interact with Systemd. It provides a comprehensive interface for controlling and querying the state of systemd units.

Service: Service is an older tool that might be available for compatibility.