throat infection vs pharyngitis

throat infection and pharyngitis both are nouns.

Word	Noun	Adjective	Verb	Adverb
throat infection	Yes	No	No	No
pharyngitis	Yes	No	No	No

As nouns, pharyngitis is a hypernym of throat infection; that is, pharyngitis is a word with a broader meaning than throat infection:

throat infection: an infection of the oral pharynx and tonsils by streptococcus
pharyngitis: inflammation of the fauces and pharynx

Other hypernyms of throat infection include raw throat, sore throat, infection.

throat infection (noun)	pharyngitis (noun)
an infection of the oral pharynx and tonsils by streptococcus	inflammation of the fauces and pharynx