Pijul is a CRDT. The main new idea is that it the smallest generalisation of text files that is a CRDT while keeping important properties such as the relative order of parts of the file.
You can find an explanation of how it works at [0]. The vague notion of "patch commutation" is central to both operational CRDTs and Pijul's theory of patches, but other than that, I don't really see any similarities.
