public defender vs lawyer

public defender and lawyer both are nouns.

Word	Noun	Adjective	Verb	Adverb
public defender	Yes	No	No	No
lawyer	Yes	No	No	No

As nouns, lawyer is a hypernym of public defender; that is, lawyer is a word with a broader meaning than public defender:

public defender: a lawyer who represents indigent defendants at public expense
lawyer: a professional person authorized to practice law; conducts lawsuits or gives legal advice

Other hypernyms of public defender include attorney.

public defender (noun)	lawyer (noun)
a lawyer who represents indigent defendants at public expense	a professional person authorized to practice law; conducts lawsuits or gives legal advice