A question that has been bothering me for a while know is, "What the hell is the difference between a Bureau, e.g. the FBI, and an agency, e.g. the CIA?"
Now, I'm not sure how appropriate this question is for this sub, but bare with me... I've been reading.
In my hour and a half of googling, I've found that a bureau as a department of government dates from around the 1720s and predates bureaucracy by almost a 100 years. Also I'm pretty sure that in the US govenerment, there aren't any bureaus that are independent from a specific department, unlike NASA or the CIA.
But my current question is the fact that the Bureau of Indian Affairs is called a bureau but the National Parks Service is not simply due to language use and when it was named or is there more going on? Are all sub-departments technically bureaus and only some of them have snazzy names? Is the fact that the department of education seems to only have offices because it's not even 35 years old?
Inquiring minds want to know.
Government bodies with bureau in the name are often a subdivision of a larger agency. The FBI's parent agency is the Department of Justice. The Bureau of Indian Affairs is part of the Department of the Interior. That said, the National Park Service is also part of the Department of the Interior. That the one has bureau in the name and one doesn't has no legal significance–it's purely a question of naming.
The IRS is part of the U.S. Department of the Treasury, the Patent and Trademark Office is part of the Department of Commerce, the Food and Drug Administration is part of the Department of Health and Human Services (and prior to 1940 was part of the Department of Agriculture), etc. It's just the name that Congress chose to give them.
All of the examples you gave, by the way, ARE agencies. They all have statutes that outline their authority and area of influence. That the FBI doesn't have agency in its name and the CIA does has no legal significance. Both are agencies as a matter of administrative law.