It will s mostly dependent on the age of the bird. Young fast growing birds are great for fryers and grillers. Generally a lot smaller then your broiler but processed at about the same time (I see Murray McMurray puts leghorns in that group that would be very little meat)
Broilers are your Cornish x, and other hybrids. They are fast growing and generally similar to what you would find at the supermarket.
Roasters are your more traditional heritage birds. They grow much slower and so require a longer cooking time. Their flavor should be stronger too.
Soup birds are your very old birds. Many a mean Rooster has ended up as soup. They require the longest to cook to get tender.
How they are proportioned depends on the breed you choose. The broilers will have the large breast meat, the roasters will be more leggy.