Aggressive at 2 weeks? Rooster traits?

We just got 2 barred rock and 2 rhode island chicks. They are all 2 weeks old. Yesterday we added 2 Easter Egger chicks to the bunch, which I was told were 2 weeks old. They are at least a head taller than the other 4 - is this just a breed difference?

For the most part they all get along; sometimes they all sleep together, at other times the 2 EEs are paired up and the other 4 are on the other side of the brooder.

One of the EEs has taken to hopping up on top of water (mason jar size) - is this early for 2 weeks old?

I've also seen the EEs having a stand off more than once, standing fully erect with their heads out towards each other and then they run at each other. It honestly looks like what 2 roosters would do, but I feel like it would be early to tell gender based on behavior. Are there tell-tale signs of a roo in a chicks behavior this early on?

I've never had chicks before though, just going based off what I've read so sometimes interpreting that into my brooder at home is perplexing! Thank you for any input!

Not a very good picture but here is one of the EEs atop the water dish.

Is the EE chick in question picking on the other chicks? Are you sure the EE chicks are only 2 weeks old?

pullets establishing a pecking order will chest bump, stand tall to one another but one thing I've seen my young cockerals do before they got RE Homed was run and jump feet first as if spuring the others. I've only seen males do this. if it's just pecks and standing erect and chest bumps, could be the girls establishing their order. wait and see if she/he gets more aggressive and protective it could be male. I had a male once who pecked my hand when I'd go to touch the other birds or feed. turned out he was definitely a he.

I confirmed with the lady I bought them from that they are in fact 2 weeks old. She said they were growing much faster than her other chicks too and just seem to be big! It seems to have mostly settled down with the other chicks. I've never seen the "spurring" yet, just a lot of very tall standing and obviously trying to intimidate each other. I guess only time will tell!

I have 6 chicks 8 weeks old and I was certain at one time that at least one of them was a rooster based on the behavior but turns out they're all hens so I think It was just their pecking order nonsense. It's a very strange social order that science doesn't even FULLY understand yet. I'm not saying you don't have a rooster but even pullets can be jerks that resemble rooster behavior. In my opinion..

Female chicks will spar like that.....I've seen a hen use her feet to fight before.
Put a funnel on top of that waterer to keep them off it.

Easter Eggers are not a breed, they are just chickens that should have the blue egg gene and the pullets might lay blue or green eggs. How those chicks grow just depends on what other breeds are in them. It does sound strange that they would be that much bigger. Chicks grow really fast. I wouldn’t be too surprised if they were closer to three weeks than two.

Like others I’ve seen pullets spar like that. Males are more likely to do that than females but you certainly cannot sex them at that age by that behavior. I’ve seen adult hens spar with adolescent cockerels and put them in their place. I can’t remember for sure if she used her feet but I think she did.

The reason Aart suggested putting something on that waterer to keep the chicks off is that they might turn it over and create a wet mess or they will poop in the water so you will need to change it often. Instead of putting something on mine I hang something over it to keep them from perching up there. A plastic milk jug with sand in it for weight is pretty popular but I had some wood handy so I hung that.

In about three weeks you might start a new thread and post photos of the chicks showing a close-up of the head, especially comb and any wattles. A profile shot showing posture and legs can also be very helpful. Often at five weeks chicks start to show sexual differences but not all do that. I’ve had a few that were still uncertain at more than twice that age but often five weeks gives some really good clues.

Is that red glow from a heat lamp? Is the chick up there because it is warmer?