It is the extra space given to the chicken while it is growing, whether indoors or outdoors, that makes the difference in meat texture. It has nothing to do with the quality of meat, its fat content, or how it was raised. It is a marketing tool only. All chickens are naturally white skinned. Depending upon contents of the feed, including the use of corn versus wheat in the feed formula, the resulting color will vary accordingly from pale white to bright yellow and all shades in between.
Antibiotics cost the grower money.
They are used because they save money in feed costs and reduce mortality. It takes about 2-3 weeks longer to reach the same weight without antibiotics than with them. The USDA's definition pertains only to how the chicken is processed, i.e. whether any substance, such as a basting additive, is injected into the bird at the processing plant. It has nothing to do with how the bird is raised, what it is fed, or what it is medicated with, as long as no artificial ingredient is administered. Nobody does it.