typhus vs urban typhus

typhus and urban typhus both are nouns.

Word	Noun	Adjective	Verb	Adverb
typhus	Yes	No	No	No
urban typhus	Yes	No	No	No

As nouns, urban typhus is a hyponym of typhus; that is, urban typhus is a word with a more specific, narrower meaning than typhus:

typhus: rickettsial disease transmitted by body lice and characterized by skin rash and high fever
urban typhus: acute infection caused by rickettsia and transmitted by the bite of an infected flea; characterized by fever and chills and muscle aches and a rash

Other hyponyms of typhus include endemic typhus, murine typhus, rat typhus.

typhus (noun)	urban typhus (noun)
rickettsial disease transmitted by body lice and characterized by skin rash and high fever	acute infection caused by rickettsia and transmitted by the bite of an infected flea; characterized by fever and chills and muscle aches and a rash