postdoc vs bookman

postdoc and bookman both are nouns.

Word	Noun	Adjective	Verb	Adverb
postdoc	Yes	No	No	No
bookman	Yes	No	No	No

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

postdoc: a scholar or researcher who is involved in academic study beyond the level of a doctoral degree
bookman: a learned person; someone who by long study has gained mastery in one or more disciplines

Other hypernyms of postdoc include investigator, research worker, researcher, scholar, scholarly person.

postdoc (noun)	bookman (noun)
a scholar or researcher who is involved in academic study beyond the level of a doctoral degree	a learned person; someone who by long study has gained mastery in one or more disciplines
a grant that funds postdoctoral study or research