Is it normal some people don't have double chins but they're really obese?

I notice that I have a double chin because when I look down even just a tiny bit, my chin folds and I get the double chin. Even when I'm looking straight out but slightly down in photos, just a smidgen, you can see my double chin but I'm a normal weight...

Then there's my friend Fatty Patty (she nicknamed herself that to make light of her obesity). She's not just chunky or slightly obese, no, she's pretty damn large..think elephant, that's her. She has no double chin at all. She looks straight, no double chin, looks down slightly like me, there's no double chin! I am so confused by this madness. What is this?! Why is this so!? I have one but she does not and she's 3X my size..why is this? I can't seem to figure it out. In photos when we're laughing together and it's just our faces/shoulder areas, I look 3X bigger than her because I am looking down amd I have a big double chin but she's looking down and still has a thin thin chin with no double.

Why is this? I am confuzzled. Is this normal? I don't see this on many others..just her.