washup vs sponge bath

washup and sponge bath both are nouns.

Word	Noun	Adjective	Verb	Adverb
washup	Yes	No	No	No
sponge bath	Yes	No	No	No

As nouns, sponge bath is a hyponym of washup; that is, sponge bath is a word with a more specific, narrower meaning than washup:

washup: the act of washing yourself (or another person)
sponge bath: you wash your body with a sponge or washcloth instead of in a bathtub

Other hyponyms of washup include shower, shower bath, bath, steam bath, Turkish bath, vapor bath, vapour bath.

washup (noun)	sponge bath (noun)
the act of washing yourself (or another person)	you wash your body with a sponge or washcloth instead of in a bathtub
the act of washing dishes