Agree with above. Hard to tell whether you've got a Barred Rock pullet or Black Sex Link male, at this point. You'll know soon enough. At 5 weeks, the BSL male will sprout a pink comb and tiny red wattles. If the black chick maintains a yellow comb and sprouts no wattles, by 5 weeks, you've likely got a pullet.
The red bird is hatchery quality and likely a production red of some kind. If a pullet, she would be a great layer.