The main changes can be summarised as follows:
Art. 14 – the abusive conduct of a party forcing the other to terminate a contract or amend its terms entitles the other party to terminate the contract with just cause.
Art. 14bis – “Just Cause” now includes outstanding salaries (2+ months).
Art. 17 – compensation owed to a player is now “mitigated” if the player has in the meantime found a new club prior to the FIFA decision. However, “Additional Compensation” (3 to 6 monthly salaries) is owed by the club if the breach is due to overdue payables.
Art. 18 – “grace periods” for salary payment are no longer allowed, but collective bargaining agreements prevail.
Art. 24bis – DRC or PSC shall impose “temporary” sporting sanctions on players (playing ban) or clubs (registration ban) until the debt is paid.
More information available here