Is it possible to generate changelog diffs?

I've got my baseline snapshot created using the generateChangeLog command. I've made some changes and I'm trying to figure out how to generate a changeset file by doing some sort of diff but it seems like that isn't a concept in Liquibase and those need to be created manually. XML also appears to be the preferred format but are we expected to hand-write xml files? Seems like this could be automated easily?