2 Week old Australorps

[k9lin]

I incubated some Australorp, EE, and SLW eggs that I got from My Pet Chicken, which hatched on March 30th. They are 2 weeks old now. There is a significant size difference between the Australorps - some are much bigger than others - and the ones that are bigger have tail feathers already. The tail feathers appear to be more long and pointy. The others don't, or are just starting. As well, one of the SLW has tail feathers, and is almost twice the size of the other one. Both of the EE's have tail feathers and are nice sized. All of the chicks are eating and appear healthy. Would the larger chicks be the cockerels? Do the boys grow the tail feathers first? Can't tell anything from the combs yet. Just curious, as I was expecting to see differences around 6 weeks. Thanks!