GeekTool is a macOS application that lets you customize your desktop with great flexibility. Developed by Tynsoe projects
License: Free
Screenlets is both a Python framework to simplify writing Cairo-drawn desktop widgets, similar to those found in the "Dashboard" feature of OSX, and a collection of widgets written using the framework. It is designed to work with any modern Linux desktop. Developed by Rico Pfaus, Helder Fraga, Natan Yellin
License: Open Source
GeekTool is ideal for advanced users seeking extensive customization and scripting capabilities, while Screenlets caters to beginners with its user-friendly interface and pre-made widgets. Both tools serve the purpose of displaying information on desktops, but their target audiences and functionalities differ significantly.