leaflet vs blue book

leaflet and blue book both are nouns.

Word	Noun	Adjective	Verb	Adverb
leaflet	Yes	No	No	No
blue book	Yes	No	No	No

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

Other hyponyms of leaflet include ticket book.

leaflet (noun)	blue book (noun)
a thin triangular flap of a heart valve	a register of persons who are socially prominent
a small book usually having a paper cover	a report published by the British government; bound in blue
part of a compound leaf	a blue booklet used in universities for writing examinations