CAA = Civil Aviation AUTHORITY = Controlling organisation
FAA = Federal Aviation ADMINISTRATION = Enabling organisation
Similar in a way to other US vs UK things, e.g....
Prime legislation in the UK = Official Secrets Act - if you want to know about your own government you need to ask and they may say you don't need to know
In the US = Freedom of Information Act - the government makes data freely available
Quite funny that there's a polarising change going on now though. US introduced the Patriot Act (which allows it to intercept and confiscate books, publications, computers, etc. at the border). The UK has introduced the Freedom of Information Act which gives it a formal process to still say you can't access its data.