Ok! I found the answer - the rear bar sits higher from the roof (that’s because the roof is a few cm lower than the floor at the back, so it compensates for it).
So if you need to be sure, just measure the bar height from the roof. I measured on the split between the bar and the mount, so it’s consistent. I used the included measurement tape - the difference was significant, around 8cm vs 4cm.
The funny part is I cruised around town until I found another model Y with the roof rack and compared.