The one on the right is Kylie Jenner, but you probably already knew that, since Kylie's look is pretty locked in and definitive at the moment -- and there's no mistaking her for any of the other Kardashians or Jenners ... these days, at least.
Kendall, however, looks more and more like her older half-sister Kim as the days go by, as she becomes fully ensconced in being 18 legal years old and able to do -- ahem -- whatever it is she wants with her body and physical appearance.
Looking good, ladies. But especially you, Kendall. Goodness, that is one pretty face.