Salmon faverolle 3 week chick “off behavior”

[DemeChick]

This supposed pullet is a bit larger and has solid white feathers on her back and wings.
One photo shows one of the regular size chicks same age.

This morning I thought maybe she was napping but her breathing seems a bit rapid.

Any and all observations welcome.

 

[LaFleche]

The bigger one does not look like salmon faverolles to me. How old are they and where did you purchase them?

Does the smaller chick in the last picture have an injury on the left wing/shoulder or are there just the new feathers coming in?

They seem to feel cold, what kind if heat source do you provide and how does their poop look?