writing board vs work surface

writing board and work surface both are nouns.

Word	Noun	Adjective	Verb	Adverb
writing board	Yes	No	No	No
work surface	Yes	No	No	No

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

writing board: work surface consisting of a wide lightweight board that can be placed across the lap and used for writing
work surface: a horizontal surface for supporting objects used in working or playing games

writing board (noun)	work surface (noun)
work surface consisting of a wide lightweight board that can be placed across the lap and used for writing	a horizontal surface for supporting objects used in working or playing games