I purchased eight brown leghorn chicks sexed at a local feed store. Three of them have much larger combs and seem a little more aggressive then the others. Below is a picture of one of the birds in question:
They are 6 1/2 weeks old. There is no sign of crowing yet, they are all very quiet. Any thoughts? Their coloring is a little different then the other five as well. In my area we are not allowed to have roosters, and I have no use for them as I only want eggs. Anything you can tell me to help figure this out is much appreciated as I am new to chickens. I am hoping they are just a slightly different breed.
Thanks in advance for the help.

They are 6 1/2 weeks old. There is no sign of crowing yet, they are all very quiet. Any thoughts? Their coloring is a little different then the other five as well. In my area we are not allowed to have roosters, and I have no use for them as I only want eggs. Anything you can tell me to help figure this out is much appreciated as I am new to chickens. I am hoping they are just a slightly different breed.
Thanks in advance for the help.