The Wyandotte... yeah, that's some epically bad lacing. If it weren't for the yellow legs, I'd be tempted to call it a Hamburg. It may look better after molting. Comb looks a bit red for a young pullet, but I've had young SLW pullets redden up early and the legs are fairly dainty, so I'd hold off for a few weeks before deciding.
Mostly looks. Hatchery birds typically start laying sooner than heritage bred birds of the same breed, and may have higher production in the early years. Heritage hens tend to have more productive years, though.
so glad to hear that she is looking like a hen, I don't have any 2 of the same bird just yet so have nothing to compare her too. I do think she is pretty just had hopped to have good lacing... But if she is a hen that will make me very happy!