What breed is this?

[JedJackson]

@JedJackson -is it just me or does that look a bit like a pea comb? It seems too large this age either way to be a pullet.

Yes, it looks like both the black bird and the naked neck have pea combs. So the black one cannot be an Australorp. I do think it is a cockerel due to comb size. I think the naked neck is a pullet.

 

[JedJackson]

Can you please give me tips in identifying a pullet and a cockerel.

Your chickens are really too young to sex, in my opinion. I thought the black one was a cockerel because its comb seems so large for that age. But you are better off and will get better answers if you wait until your birds are feathered out, at about 7 weeks old. Look for larger, red combs at that age, and those will be your cockerels. You can also post new pictures in here at that point if you want more opinions.

I think your chickens are mixed breeds, but that will be easier to tell when they get older, too.