Here's how inverted question mark looks like with a bunch of font I've just chosen without any particular system in my mind.
Those are very different fonts however in all of them the inverted question mark is visually very distinctive from the regular question mark. It's sort of looks bulkier as a rule of thumb.
My question would be - when it comes to typography, is reverted exclamation mark supposed to be completely symmetrical to the regular one or it differs in the majority of fonts? If what we see on the picture is completely fine, are there nevertheless some fonts where those marks are symmetrical?
Also, what about handwriting?
UPD: Guys I'm so stupid - like high class stupid, like very very stupid - it was indeed just bold typeface - however even this situation you've provided some very relevant and interesting data so I won't delete this particular question - let it be a monument to my stupidity and your amiability!