work bench vs workbench

work bench and workbench both are nouns.

Word	Noun	Adjective	Verb	Adverb
work bench	Yes	No	No	No
workbench	Yes	No	No	No

As nouns, work bench and workbench are synonyms defined as:

work bench and workbench: a strong worktable for a carpenter or mechanic

Other synonyms of work bench include bench.

work bench (noun)	workbench (noun)
a strong worktable for a carpenter or mechanic	a strong worktable for a carpenter or mechanic