Puppy food (kibbles) has higher protein content as adult food.
I feed my "under eaters, skinny Papis, Papis under stress, pregnancy, post illness if any, all puppy chow, even as adults.
Only the gulpers, pudgy Papis get adult food.
Also if a Papillon of mine is very fit and active (athletic) I keep feeding puppy food.
The ones who do not want to play much and are kind of lazy, get adult food.
This should give you a guide line. (I hope)