tabletop vs work surface

tabletop and work surface both are nouns.

Word	Noun	Adjective	Verb	Adverb
tabletop	Yes	No	No	No
work surface	Yes	No	No	No

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

tabletop: the top horizontal work surface of a table
work surface: a horizontal surface for supporting objects used in working or playing games

tabletop (noun)	work surface (noun)
the top horizontal work surface of a table	a horizontal surface for supporting objects used in working or playing games