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If the comb is significantly redder than the other two, than maybe it's a roo, but... not because the comb is wider (EE pullets can have the wide bumpy comb also). From the photos you posted, its comb looks pink, not red - pink is a normal comb color for 10 week old pullets.
Also the size of the chick is not a deciding factor with EEs either - they are not purebred and have variations. My older pullet (second picture I posted on the previous page) was quite a bit larger and heavier than the other two EE chicks I had at that time and along with her larger, wider comb, I was convinced she was a cockerel up until she was about 15 weeks old - she now lays the olive eggs in my avatar.
As for being aggressive - pullets will chest bump with each and start things up too - that's how they establish pecking order - this chick may end up being the leader of the flock.