Some egg labeling facts from How to Cook Everything:
ORGANIC (CERTIFIED ORGANIC) The USDA Certified Organic stamp means the hens are raised without cages and with access to the outdoors; are fed organic, all-vegetarian diets; are raised without antibiotics, pesticides, or insecticides; and that the eggs aren't irradiated.
Certified Organic is the only way to guarantee that your eggs were raised without antibiotics. A new term, Beyond Organic, is gaining recognition as being stricter than the USDA Certified Organic standards, though it isn't USDA regulated. But you probably won't see it in a grocery store.
CERTIFIED HUMANE, FREE FARMED, AND ANIMAL CARE CERTIFIED Technically separate, these all refer to the animals' living conditions, guaranteeing a minimum amount of space; access to fresh air, water, and food; and limited stress and/or noise, among other things. The certification is overseen by independent associations whose inspection regulations are approved by the USDA, but they are not part of a USDA regulatory program.
Participation is voluntary. These eggs are not organic unless separately labeled so.
The following group are the labels the USDA allows producers to use on an honor system, without formal oversight or inspection:
FREE-RANGE (AKA FREE-ROAMING) Implies that the birds are not kept in cages and sometimes have outdoor access, though it can be just a door open at some point in the day. Free-range as defined by the USDA applies only to chickens used for meat and not egg layers, so there are no USDA standards for so-called free-range eggs.
CAGE-FREE The birds are not kept in cages, but no outdoor access is guaranteed.