Different Sized Chicks?

[TexGal]

I'm new to chickens and plan on getting some at TSC next week!! When I was in there the other day I noticed some were about a week older than others and obviously bigger, but there were several who looked so very tiny in the new shipment. Which of course draws my eye to them. Are the tiny ones just younger, or is the possibility of complications down the road much higher? Because they are so darn cute

 

[AlienChick]

TSC may have gotten a shipment of bantam chicks.
They will be very tiny when compared to their large fowl counterparts.