Binary diffs. But depending on the file, it might not really be of much help (I know for a fact that Adobe premiere projects for example are nearly completely different every time you save).
Folio uses git internally and as such is based on binary diffs. To tackle the issue of an ever-growing repository, we're looking into integrating git-lfs which supports offloading blobs from the repository.
So is there a way to achieve collaboration? if this is based on binary diffs, can we still have merging?