Apart from eligibility, it's tough to know the difference - same duration, same number of questions, same objectives in the exam guides.
In theory, the 622D should ask more on what's different between 6.0 and 6.5, given that it's only taken by VCP6-DCV holders.
Have you tried playing "spot the difference" between those 2 pages??
That's actually kind of messed up. The Delta Exam Guide should be focused on the Delta subject material - migration, new features, changes, that sort of thing. By copying the full VCP 6.5 Exam Guide it could lead you to wasting a lot of time studying for stuff the exam (in theory) should not cover.