Curse Compare is a tool to find differences between modpacks. The tool will analyze the dependencies of two Curse modpacks and generate three lists: mods that both projects contain, mods that only project #1 contains, and mods that only project #2 contains.
Downloads available on the Releases page.
Curse Compare can be used in two ways: the GUI or the command line. To use Curse Compare's GUI, just double click the jar file or execute it via command line with no arguments. Command line usage requires two arguments, corresponding to project URLs.
URLs provided in both the GUI and command line must be for projects on either minecraft.curseforge.com or feed-the-beast.com. For example, here are two valid URLs.
https://minecraft.curseforge.com/projects/agrarian-skies-2