lapboard vs writing board

lapboard and writing board both are nouns.

Word	Noun	Adjective	Verb	Adverb
lapboard	Yes	No	No	No
writing board	Yes	No	No	No

As nouns, writing board is a hypernym of lapboard; that is, writing board is a word with a broader meaning than lapboard:

lapboard: writing board used on the lap as a table or desk
writing board: work surface consisting of a wide lightweight board that can be placed across the lap and used for writing

lapboard (noun)	writing board (noun)
writing board used on the lap as a table or desk	work surface consisting of a wide lightweight board that can be placed across the lap and used for writing