I think the enriched cage as mentioned above is one with marginally more space, introduced in response to the backlash against the original battery systems.
I have been shown around a large-scale 'freerange' set-up - ie warehouses housing thousands of chickens with automated feeding, egg-collecting and faeces-removing systems, and small doors so that theoretically they can range outside and a few do. Frighteningly far from what we think of as free range, and illustrates the labelling problems when this is labelled the same as what we sell off the small-holding. This is what allows supermarkets to sell large quantities of free range eggs. Most people buy in ignorance of the true origin of these free-range eggs, feeling they are assisting in improving chicken welfare. Perhaps they are to a marginal degree, but in welfare terms it seems to me little different from a battery system; however this is the way to go for largescale producers and brings a price premium for them and for the supermarkets.
But looking at the other side how otherwise are people going to get supplied with eggs at a price they are prepared to pay?
Some similar aspects to the milk production/supermarket issue.
It can certainly get depressing thinking about these things too much!