There are multiple tools that distros use to manage packages, including both text-based and graphical tools. Debian uses the venerable APT package manager, with Aptitude as the CLI front-end and Synaptic as a graphical manager. Since Debian places great significance on stability, it doesn’t aim to release the latest versions of most software.
Ubuntu’s package management system is derived from Debian. Besides APT and Aptitude, there’s the Ubuntu Software Center, a graphical utility for installing, purchasing and removing software. Ubuntu also has PPA (Personal Package Archive) repos and ships with support for Snap universal packages.