Difference between jessica alba's smile and a normal girls smile?

i know their is a difference just can't put my finger on it. could be the cheekbones or smile lines or jaw structure what do you think makes her smile look so cheeky ,and btw she's not the only one look at this teen model about my age http://www.on-charm.com/store.jpg if you don't know alba look at this http://www.sonfamosos.com/wp-content/uploads/2008/02/jessica-alba-144.jpg this is a normal girls smile its not as cutesy and babyish http://images.starpulse.com/Photos/pv/Jamie%20Lynn%20Spears-11.jpg but it still very nice