Its rather confusing to explain, but I will try my best. I still dont understand it fully.
Each sex in a certain variety competes against each other. (So 1st place hen, 2nd place hen, 1st place cockeral, 2nd place cockeral ect.)
The all the 1st places in the variety compete against each other or Best of Variety, and Reserve of variety. (Which is ultimately a 1st and 2nd place)
Then all the BV's and RV's from each variety (white, black, buff etc...) compete for Best of Breed, and Reserve of Breed.
Then all the Best of Breeds compete against all the other breeds in their classification for Champion and Reserve Champion. (In my case Silkies were judged against all the other featherlegs...)
And that is the best that I can understand it at this point. Its kind of like a tournament. There are brackets of games, and each winner moves up a notch until it is either beaten, or it comes out as champion.