TSA vs bureau

TSA and bureau both are nouns.

Word	Noun	Adjective	Verb	Adverb
TSA	Yes	No	No	No
bureau	Yes	No	No	No

As nouns, bureau is a hypernym of TSA; that is, bureau is a word with a broader meaning than TSA:

TSA: an agency established in 2001 to safeguard United States transportation systems and insure safe air travel
bureau: an administrative unit of government

Other hypernyms of TSA include agency, authority, federal agency, government agency, office.

TSA (noun)	bureau (noun)
an agency established in 2001 to safeguard United States transportation systems and insure safe air travel	furniture with drawers for keeping clothes
	an administrative unit of government