bathing tub vs hip bath

bathing tub and hip bath both are nouns.

Word	Noun	Adjective	Verb	Adverb
bathing tub	Yes	No	No	No
hip bath	Yes	No	No	No

As nouns, hip bath is a hyponym of bathing tub; that is, hip bath is a word with a more specific, narrower meaning than bathing tub:

bathing tub: a relatively large open container that you fill with water and use to wash the body
hip bath: a bathtub in which your buttocks and hips are immersed as if you were sitting in a chair and you bathe in a sitting position

Other hyponyms of bathing tub include footbath, hot tub, sitz bath.

bathing tub (noun)	hip bath (noun)
a relatively large open container that you fill with water and use to wash the body	a bathtub in which your buttocks and hips are immersed as if you were sitting in a chair and you bathe in a sitting position