aptitude is a terminal-based apt frontend with a number of useful features, including: a mutt-like syntax for matching packages in a flexible manner, dselect-like persistence of user actions, the ability to retrieve and display the Debian changelog of most packages, and extreme flexibility and customization.
License: Open Source
npm is a package manager primarily for JavaScript and Node.js, offering a vast ecosystem of packages and version control, while aptitude is a package manager for Debian-based systems focused on system software management and dependency resolution. The two serve different purposes, with npm catering to developers in the JavaScript ecosystem and aptitude serving system administrators and users of Debian-based distributions.