Do you know if she has taken a look at the website herself? If so she likely chose the one she wanted specifically. If not it’s possible she just picked the same one as her friend and didn’t know they had other styles. I actually found the dauphine key holder to be more feminine, but it is quite pricey for a key holder. The mini pochettes are even cheaper (more bang for your buck haha) and other SLGs are in the same ballpark. Is her heart set on a key holder?
I’m not sure about the size difference but they seem to be similar lengths.
Sorry I couldn’t be more help but I got my first vernis cles when I was 13 and your post brought back the sweet memories I have of that. I still use it to this day! I hang my car keys off the hook and keep my cards inside of it for when I don’t want to carry a wallet or purse; it was perfect for a low maintenance teen.