Those are two completely different lists. One is “the promoter group” and the other is “everyone involved” which are in no way equivalent. It’s like the opening credits on a movie, vs the closing credits. One of the two is inherently going to be more detailed.
They did work collaboratively towards a standard. They just also in parallel worked on their own project, because they know standards can take an indefinite amount of time, so it could have been a decade to get USB C fleshed out, while they had already been working on Lightning in the background.