bath linen vs bath mat

bath linen and bath mat both are nouns.

Word	Noun	Adjective	Verb	Adverb
bath linen	Yes	No	No	No
bath mat	Yes	No	No	No

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

bath linen: linens for use in the bathroom
bath mat: a heavy towel or mat to stand on while drying yourself after a bath

Other hyponyms of bath linen include bath towel, face cloth, flannel, washcloth, washrag.

bath linen (noun)	bath mat (noun)
linens for use in the bathroom	a heavy towel or mat to stand on while drying yourself after a bath