Orpingtons are always supposed to have white shanks, just like Wyandottes are always supposed to have yellow shanks. The shank color is a breed trait, just as much as the feather color or comb type or egg color or general body shape.I see that you’re right - most don’t seem to have yellow legs, but I just found this pic online of a splash orp and this one has yellow shanks! I wonder if they are always white?
Light Brahmas and Columbian Wyandottes have the same color pattern and lay brown eggs. But the combs are different (pea for Brahma, rose for Wyandotte: different genes and different appearance), and the feet are different (feathered for Brahma, clean for Wyandotte). There are other differences too, like size, that do not show up as well in photos.I didn’t know brahama had feathered feet but Columbian wyandottes have naked legs. Probably a rooky mistake. I’m still prepared to say they’re the same birds
Saying Light Brahmas and Columbian Wyandottes are "the same" would be like saying all black dogs are "the same," even if one is a Labrador Retriever, one is a poodle, and one is a Chihuahua.