Exact difference between "Go To Previous Edit Point" AND "Go To Previous Edit Point On Any Track"?

I am creating what is essentially a glorified slide show. Lots of still pictures, and a few videos mixed in.  Most of my "clips" are photos, and therefore have no sound. So I was baffled when I used the up and down arrow keys and the playhead seemed to jump around randomly, and certainly not to the next 'clip' (still photo).

I am focusing on the video (mostly still photos) track and couldn't see the audio track. When I shrank the tracks down so I could see audio, it then seemed like the up and down arrow keys were jumping from one audio clip to the next -- not still photo 'clips'.  But actually what is happening is the up and down arrow keys are only jumping between actual video clips (which have audio) and not still photo 'clips'.

So to get expected behavior, I have to use the SHIFT-arrow keys -- Go To Previous Edit Point On Any Track -- shortcut just to jump between my bazillion still photos. Which is non-intuitive, to me anyway.  Why on earth does Go To Previous Edit Point mean ignore photo clips and only go to video clips? Is a still photo 'clip' not an edit point?  What exactly is an "edit point"?  Is this something everyone else know and didn't tell me??  😋

(I guess I could just remap/swap the keyboard shortcuts and I would then get the behavior I had expected.)