blacksmith vs metalworker

blacksmith and metalworker both are nouns.

Word	Noun	Adjective	Verb	Adverb
blacksmith	Yes	No	No	No
metalworker	Yes	No	No	No

As nouns, metalworker is a hypernym of blacksmith; that is, metalworker is a word with a broader meaning than blacksmith:

blacksmith: a smith who forges and shapes iron with a hammer and anvil
metalworker: someone who works metal (especially by hammering it when it is hot and malleable)

Other hypernyms of blacksmith include smith.

blacksmith (noun)	metalworker (noun)
a smith who forges and shapes iron with a hammer and anvil	someone who works metal (especially by hammering it when it is hot and malleable)