Both definitions are useful. Different pay for the same work is obviously unjust at the surface because it affects individuals. But a different mixture of jobs that leads to unequal pay, while it doesn't involve anything so easy as pointing at an individual to blame, still hints at a structural problem in our society.
Not necessarily. It can point to different distribution of priorities between sexes. E.g. if women prefer to dedicate their energy to family and house, while men prefer to work more, it makes sense that men would earn more. If we quit assuming we all want the same thing and actually ask people what they want, we may actually learn something. There are studies that do ask this kind of questions and get interesting answers, and my complaint is that this study is not actually one of those, it only appears to be that on the surface.
Not an disagreement, but a rather large detail is that it isn't the distribution of wants and needs that determine the distribution of priorities but rather the strategies employed to reach those wants and needs. If the strategies diverge then so do the priorities.
