does for example the first image indicate that the head is printed toward printer in addition to face up/down indication?
Because for example on some machines (e.g. 7328) if you set Standard Paper in tray settings it prints with the same orientation as you load paper: face up, head toward the machine. But if you set Letterhead Paper, prints come out face-down and rotated 180°. What I mean is that there's no indication of how a printer/MFP prints normally and how instead it prints if you change paper settings...
The trays have a picture of paper with lines on it, the lines tell you which side is printed first. One edge is folded, if the lines are on the folded bit, it prints on the side facing down.
So, in picture examples, these print on the side of the paper facing the floor
This one shows it prints on the side facing up
is there a way to know for each Xerox MFP or printer on which side of the paper and with which orientation does it print? User guides show how to load paper but nowhere it's said why to do so. I've noticed that almost any different model has its own way to print so it could be useful to know how to properly load paper knowing how printer really works.