The hatcheries originally named them Golden Sex-Links, and people like to nickname things in a confusing way so they are more commonly known as Golden Buffs, even though that would not be correct for a breed name.
Golden Buffs, also called Golden Sex-Links or Golden Comets, is a hybrid and mixed strain of chickens made specifically for egg production. I am not sure what you are saying that is confusing you in particular. What do you mean?
Chickens can typically be sexed at six weeks old if they are a normal-feathering breed (meaning that they do not feather slowly or more quick than usual). Your Buff Orpington appears to be a pullet, but can we get a picture of the chicken standing normally?
Buff Orpington.
Buff isn't a breed, buff is a color. The Orpington is a breed, though, and the most popular variety would be the Buff Orpington. In fact, it is so popular that many people mistakenly believe that there is no other color of Orpington.