Unlike rimpy it is both open source and still getting updates, besides that I'd say functionality is basically the same

I never used RimPy since I play one a mac. It seems to me that most features that are in RimPy have also been included in RimSort, including searching in mod files, troubleshooting tools and texture compression.

If it's anything like RimPy it lets you organise mods without having to load into the game first. Super useful if you've got hundreds of mods and the game takes an hour to boot up.

It's for sorting mods in the correct load-order to avoid errors. You can also convert steam-mods to local mods to prevent them updating, if you wish.

Yup, for Ludeon or gog purchases p.e..