The only real difference I spot in the diff is ISRG not storing your certificate in its repository anymore.
The main updates are: we now link to instructions on choosing a revocation reason if you revoke a certificate. This is a requirement for Subscriber Agreements from all Certificate Authorities as of this year. Also, we've removed unneeded capitalization, removed a section that is redundant with our Certificate Policy (CP), and tweaked the wording of the requirement to "assure" control of your private key so it matches the Baseline Requirements (BRs).