drumbeat vs rub-a-dub

drumbeat and rub-a-dub both are nouns.

Word	Noun	Adjective	Verb	Adverb
drumbeat	Yes	No	No	No
rub-a-dub	Yes	No	No	No

As nouns, drumbeat and rub-a-dub are synonyms defined as:

Other synonyms of drumbeat include rataplan.

drumbeat (noun)	rub-a-dub (noun)
a vehement and vociferous advocacy of a cause	the sound made by beating a drum
(military) the beating of a drum as a signal for lowering the flag at sundown
the sound made by beating a drum