Chick identification help!

[Joshua0272]

So I got these 4 chicks from tractor supply about 3 1/2 weeks ago and I think they are like 6 weeks old because they are almost fully feathered and in the excitement of getting them I didn't even look what kind they were, I believe that 3 are barred Plymouth rocks and the other might be a australorp but l'm not 100% sure. Also I don't think that they are all hens. The gray one is significantly bigger than the others but has a way smaller comb that is barely even there, this might just be because it is a diffrent breed but l'm not sure. The black and white ones all have characteristics of being hens and Roos so any help on sexing, identifying, aging, them would be greatly appreciated!

Also if it helps anyone the black and white chicken in the last picture is a little bit heavier and larger than the other two black and white ones.

 

[Poultry Kitten]

The bottom three look like Barred Rock chicks the top one may be a Sapphire Gem.

 

[The Welch Chickens]

The top gray one has the exact same coloring as our Prairie Bluebell Egger

 

[The Welch Chickens]

The bottom three look like Barred Rock chicks

I agree

 

[LuciferRoo]

Yes, the bottom 3 look like Plymouth Rocks.
The last ones I bought were the same breed.
The fun part will be figuring out if they are male or female. Based on the coloring /shade, I am guessing all these are girls.
From my limited experience they look like females. Females are more dark gray with light gray highlights and males are light gray with dark gray highlights. Females will also have darker legs.