talcum vs bath powder

talcum and bath powder both are nouns.

Word	Noun	Adjective	Verb	Adverb
talcum	Yes	No	No	No
bath powder	Yes	No	No	No

As nouns, bath powder is a hypernym of talcum; that is, bath powder is a word with a broader meaning than talcum:

talcum: a toilet powder made of purified talc and usually scented; absorbs excess moisture
bath powder: a fine powder for spreading on the body (as after bathing)

Other hypernyms of talcum include dusting powder, toilet powder.

talcum (noun)	bath powder (noun)
a toilet powder made of purified talc and usually scented; absorbs excess moisture	a fine powder for spreading on the body (as after bathing)
a fine grained mineral having a soft soapy feel and consisting of hydrated magnesium silicate; used in a variety of products including talcum powder