Hen or Roo?

[Painted Calls]

Cockerel

 

[Pampered chicken girl]

Cockrell

 

[Jaeden Mckinley]

At the same age

She is about 3 years old comb is a bit bigger

 

[Sussex19]

She is about 3 years old comb is a bit bigger

That makes sense, a hen (as in a female chicken older then a year) will have quite a big comb, but it only develops just before they start laying.
The one in question looks to be about 8 to 10 weeks old, so at that age a pullet would have hardly any comb.
A cockerels comb can start developing as early as 1 or 2 weeks.