I like how the teens are in Sims 4. They're much more realistic. Teens in Sims 4 are more like 16 year olds, second to last year of high school. When I was in High School most 16 year olds were at their full adult height and a lot of the boys were growing facial hair. With the University pack teens are thinking about and preparing for university which is something usually done in the later years of High School. In Sims 4 the teens do look younger than the young adults: their faces are more youthful and they are skinnier. Not much actually changes in looks between a teen and young adult in real life. I've always been able to tell the Teens apart from the young adults in Sims 4.