I just got my spring chicks and have both a Cuckoo Marans and a Barred Rock in the mix. They look very similar, and an internet search took a while to figure out the subtle differences. They both have white spots on their heads and mostly black fuzz - the main difference is that Marans legs are pink (aka white) while Barred Rocks are yellow. When going through the pictures I took of my chicks, I found two that seemed to illustrate that well: First chick is the Marans; second is the Barred Rock. No, the red toenails aren't standard, they're just for me. I don't think the white-tipped wings are necessarily a difference between the two, I think the Marans is just a little older than the BR is. I could be wrong, however. Hope that helps someone else out there who had the same question as I did.