Dr. vs bookman

Dr. and bookman both are nouns.

Word	Noun	Adjective	Verb	Adverb
Dr.	Yes	No	No	No
bookman	Yes	No	No	No

As nouns, bookman is a hypernym of Dr.; that is, bookman is a word with a broader meaning than Dr.:

Dr.: a person who holds Ph.D. degree (or the equivalent) from an academic institution
bookman: a learned person; someone who by long study has gained mastery in one or more disciplines

Other hypernyms of Dr. include scholar, scholarly person.

Dr. (noun)	bookman (noun)
a licensed medical practitioner	a learned person; someone who by long study has gained mastery in one or more disciplines
a person who holds Ph.D. degree (or the equivalent) from an academic institution