talcum vs French chalk

talcum and French chalk both are nouns.

Word	Noun	Adjective	Verb	Adverb
talcum	Yes	No	No	No
French chalk	Yes	No	No	No

As nouns, French chalk is a hyponym of talcum; that is, French chalk is a word with a more specific, narrower meaning than talcum:

talcum: a fine grained mineral having a soft soapy feel and consisting of hydrated magnesium silicate; used in a variety of products including talcum powder
French chalk: a soft white compact talc used to mark cloth or to remove grease stains

Other hyponyms of talcum include soap-rock, soaprock, soapstone, steatite, rensselaerite.

talcum (noun)	French chalk (noun)
a toilet powder made of purified talc and usually scented; absorbs excess moisture	a soft white compact talc used to mark cloth or to remove grease stains
a fine grained mineral having a soft soapy feel and consisting of hydrated magnesium silicate; used in a variety of products including talcum powder