Most of my young cockerels around that age and size don't have their tail feathers. lol The pullets always seem to develop their tails quicker. Mine are 12 weeks old right now and still most of them have tail feathers. (Cockerels) Check out the pictures I posted about a week ago and you'll see what I'm talking about.I agree the one one the branch does seem to have thick leg compared to the others and if ya look closely it appears to have a broader square back compared to the others but It had to tell as I can't see thae tail feathers.
Jim