That page about sexing chickens: ignore the part on "feather sexing" by the wings. It is wrong.
Feather sexing DOES NOT WORK on most chickens.
To produce feather-sexable chicks, you need to make the correct cross of male (fast feathering) and female (slow feathering). Then you get sons that grow feathers slowly and daughters that grow feathers quickly. (Visible in the wings if you look carefully when they hatch, much more obvious a few weeks later when the females have feathers and the males still look half-naked.)
For most chickens, whether they grow feathers fast or slowly is just a breed trait, and tells nothing about their gender.
Tail doesn't tell me anything-- I've seen chicks of both genders with long tails, and ones with no tails.
The red Cochin obviously has a comb & wattles that are rather big and red.
The white frizzle has less comb development, but it's still a bit large and very red, considering how young he is. If "he" is male, it will become much more obvious over the next few weeks.