logbook vs bell book

logbook and bell book both are nouns.

Word	Noun	Adjective	Verb	Adverb
logbook	Yes	No	No	No
bell book	Yes	No	No	No

As nouns, bell book is a hyponym of logbook; that is, bell book is a word with a more specific, narrower meaning than logbook:

logbook: a book in which the log is written
bell book: a logbook in which all orders concerning the main engines of a ship are recorded

logbook (noun)	bell book (noun)
a book in which the log is written	a logbook in which all orders concerning the main engines of a ship are recorded