My google-fu is failing me on this, because I don't know the term I'm looking for.
At the edges of a simple group shot of five or six people taken with a smartphone, there is a tendency for the faces of people at the edges to look 'flatter' and 'wider', as though they've been smeared outwards with a thumb on wet ink. It's not significantly out of focus, not blurry within the uninspiring parameters of a phone lens, just 'spread out' more than it ought to be.
Conversely, if I use my DSLR with an approximation of the same lens length - 18mm or so - I don't see this effect.
What is it called & what causes it on one lens/camera, yet not another?
I can't really provide an example, as a) I tend to only take these when I have to & also tend to throw them out as soon as I've sent them to interested parties & b) they would all be a line-up of faces who wouldn't necessarily want to be in this question. I can't blank the faces as that's the whole point of the question.