drainboard vs draining board

drainboard and draining board both are nouns.

Word	Noun	Adjective	Verb	Adverb
drainboard	Yes	No	No	No
draining board	Yes	No	No	No

As nouns, drainboard and draining board are synonyms defined as:

drainboard and draining board: a board beside a kitchen sink and inclined to drain into the sink

drainboard (noun)	draining board (noun)
a board beside a kitchen sink and inclined to drain into the sink	a board beside a kitchen sink and inclined to drain into the sink