The poultry case seems extremely full these days, and every bird has a different phrase or term on the package. It's hard to decipher what is used just for marketing and what actually holds value. Here's a helpful breakdown of the most common phrases you will find.
"Raised Without Antibiotics" or "Antibiotic Free"
Raising chickens without antibiotics means paying closer attention to their nutritional needs, working closer with veterinarians, and separating sick chickens from healthy. If a chicken does become ill the farmer will work with a veterinarian that specializes in poultry to determine if they need to use antibiotics. If they do, the chicken will no longer be allowed to be sold as "Raised without antibiotics". This is why you will frequently see two chickens from the same brand one with labeled antibiotic free and the other not.
This phrase has nothing to do with organics or GMO's.
Kosher means that it was slaughtered according to Jewish dietary law. The chicken isn't allowed to be plucked with hot water, the organs are inspected by a rabbi, and the chicken is salted to draw out the blood.
This does not mean they aren't raised without antibiotics or don't contain GMO's. However, the extra oversight makes it more costly to produce, meaning the consumer can pay as much as organic, antibiotic free, and non GMO chicken.
Organic is a highly regulated term by the USDA. It is both expensive to obtain and maintain. If you are registered organic you must feed the chickens organic chicken feed. This feed is prohibited to contain animal by-products, antibiotics, or GMO's. Farmers are also required to give the chickens access to the outdoors, more on this in free-range section. This phrase is one of the few terms that mean a multitude of things that hold value.
Pasture Raised VS. Free-Range
Both of these terms do not have a specific goverment definition. The USDA determines these case-by-case. What's mostly understood is that pasture raised and free-range chicken may sound similar, but they are some key differences. Free-range chicken usually means that it has "access" to the outside. It can be inside for its entire life, but if there is a door to the outside that the chicken can access, it can be considered free-range. Pasture-raised chicken are usually held in mobile chicken coops that roam around the farm. The chickens spend most of their days outside on the current patch of the grass their coop is on. It's important that the chickens move around otherwise they would deplete one part of the pasture. It is believed that the most humane chicken you can buy in the grocery store would be one that is both certified organic and pasture raised. It is also usually the most expensive.
PHRASES THAT HOLD LITTLE TO NO VALUE
Natural - most chickens can bear this term since it means there is no artificial ingredients, coloring, or chemical preservatives. Because we are talking about whole chickens, there aren't any possibilities that a producer can even put these items into the bird.
Farm Raised- technically speaking, all chickens are raised on a farm. This means nothing.
No Hormones- the USDA does not allow farmers to use any growth hormones when raising poultry. This phrase means nothing and is usually used to mislead the consumer.
Made in America- all chicken sold in America is raised in America except for a tiny percentage that comes from Canada. The standards of the birds from Canada have the same strictness as American raised.