Or–as I’m assuming-- is it more like it does the processing of what needs to happen and then updates them?
I did some cursory googling but I wanted to double check this.
Physics.Processing is where all the non-cloth physics jobs are processed.
Physics.UpdateBodies is where all the physics bodies have their positions and rotations updated as well as where messages that communicate these updates are sent.
All the information related to the profiler is here : Unity - Manual: CPU Usage Profiler module