I cannot tell at this young age. When the adult feathers and combs begin growing, it is easier to tell. Watch for neck and tail feathers that are longer. Also, posture and behavior. Legs that are thicker can be a clue too. Good luck!
I agree with the others; they're still too young to tell for sure. I wouldn't be completely set on going by the looks of the combs though, since some pullets grow their combs faster than others. Just keep an eye out for shiny, pointy saddle feathers and watch for what momma of a chicken lover said.
