Well it is both. There are these new pairs of underwear that actually lift and separate, a bit like the Playtex bra used to advertise. For example there is a special band under the scrotum that pushes it forward, so if you buy that particular brand of underwear, it would be showing your balls and penis off more than the classic types of underwear.
The way you sport (support?) your penis in your underwear can also make a change to its appearance. Some men like their penises to be packed facing down, some like it to be facing up a bit like when erect. ( I find it more comfortable, should an erection, even slight, occur). I must say again it depends on what sort of underwear you're wearing. If you are wearing loose boxer shorts, it's not going to stay up when flaccid, is it now?
The second thing is that some people are "growers" and some people are "showers", or so I've been told. The growers tend to have small appendages when flaccid and they can grow quite a lot when erect, thus multiplying volume severalfold. As for the showers they are naturally left with appendages that look well endowed. They wouldn't necessarily grow enormously bigger when erect, but tend to stay in a flaccid state that seems to display their manhood quite nicely, thank you.
Then there's all sorts of different sizes, as well, which means that some men will have bigger genitals than others. Being overweight may blur the crotch line somewhat, as bigger men will wear larger, looser clothes for comfort and for looks. If you look at people like
Peter Berlin (look him up if you don't know who that iconic person was) he always knew just how to flaunt his rather nicely sized appendage. But then he could afford to wear those tight tight pants (trousers), the pretty boy.
PS Thought I'd do that little search for you ... ahem... :biggrin: