https://wccftech.com/directx-12-ultimate-is-microsofts-attempt-at-unified-next-gen-graphics-on-pc-and-console/

DirectX 12 Ultimate is the latest iteration in Microsoft's API for game programming. Announced today during “DirectX Innovation Day” (a stream on Mixer that replaced the canceled GDC 2020 talk), it promises to usher in next-generation graphics across both Windows PC and Microsoft's Xbox Series X console in a much faster way than previous API advancements, as explained by Microsoft below.

Prior to DirectX 12 Ultimate, there was limited overlap between these two cycles. Even when hardware was similar, the software interfaces were quite dissimilar, discouraging aligned adoption by developers.