I've created a MOC using Stud.io, bought the pieces and built it. Since it was unstable I've changed the model in Stud.io, and now I would like to buy just the pieces I've added. I could compare both version of the model manually to get the differences, but that would be somewhat cumbersome and error prone, so I'm wondering if there is some tool to compare two models, or two parts lists?
I'm thinking about something that could for example take two BrickLink XML files, and produces a new XML containing only the parts (and amount) not present in the older version.