In May of 2019, Ghosts of Saltmarsh was released bringing official rules for naval combat in the form of Appendix A: Of Ships and the Sea. This appears to be the culmination of the published "Unearthed Arcana" versions of the same name.
However, there is still the Ships and Sailing material from the 5th Edition SRD, and there are significant differences between that and the GoSM Appendix A. I understand that this material is the Open Source information Wizards of the Coast allows people to use in their own published material. I'm just confused as to while WotC would have Open Source info that contradicted their official published material.
Question: Does WotC have two different official material for rules for naval combat? Which is the definitive set of rules?