Compared to other European countries (I'm only comparing this to the slavic countries, because I'm from one) But American women tend to be a lot more..... not developed, but yes older looking
I'll explain by just using two examples;
My friend is pretty much been in America all her life and grew up here as well as her parents. I'm from Ukraine and so are all my ancestors, etc. I'm 5-6 with an even, slip frame with B sized boobs, etc. She's the same age as me and a lot taller, large boobs and pretty much looks lime a women in Ukraine would look like when they're about 30.
THIS IS JUST AN EXAMPLE, of course there are exceptions! But ONLY in general, the body shape is a lot different as well as the faces. Women in America seam to develope a lot quicker as well, males too!
I think it has A LOT to do with the food and all of the processed food. In a lot of eastern european countries, we tend to eat home made foods, made completely from scratch and there aren't a lot of fast food restorants