It is my understanding, and I've been reading a bit about these things lately, that neither "free-range" nor "uncaged" have any clear, USDA mandated, definitions. That said, the National Organic Program (NOP) policy statement says that chickens must have an opportunity to exit the barn or other structure. They put a door in the house and let the chickens go "outside". There is no space or time outside requirement. This allows large commercial producers to market chickens as having access to something us consumers value. Note how the term "uncaged" doesn't imply access to fresh air. Uncaged poultry runs around inside a big hen house, but this is not necessarily a healthy place and they may still be dosed with antibiotics. They just aren't kept in little wire "battery cages" all day. "Free Range" usually means the birds get some time outside. Free range or uncaged are not terms that imply organic.
My cousin, avid organic farmer and owner of a CSA farm, raises pastured poultry. Her chickens live in large wire pens on pastures. They eat bugs, worms, plant bits, and what ever else chickens like. They obligingly poop on the field, fertilizing it, and the cage is moved around so they don't deplete any one spot of yummy bits. These eggs are wonderful and have a lot of flavor. Unfortunately for me, she lives in New York.
I buy chickens and occasionally eggs at Harrisons on Waukegan in Glenview. Now I'm inspired to taste test them against other eggs.