seamster vs dressmaker

seamster and dressmaker both are nouns.

Word	Noun	Adjective	Verb	Adverb
seamster	Yes	No	No	No
dressmaker	Yes	No	No	No

As nouns, dressmaker is a hypernym of seamster; that is, dressmaker is a word with a broader meaning than seamster:

Other hypernyms of seamster include garment-worker, garment worker, garmentmaker, adult male, man.

seamster (noun)	dressmaker (noun)
a person whose occupation is making and altering garments	a person who makes garments