pig iron vs spiegel

pig iron and spiegel both are nouns.

Word	Noun	Adjective	Verb	Adverb
pig iron	Yes	No	No	No
spiegel	Yes	No	No	No

As nouns, spiegel is a hyponym of pig iron; that is, spiegel is a word with a more specific, narrower meaning than pig iron:

pig iron: crude iron tapped from a blast furnace
spiegel: pig iron containing manganese; used as a deoxidizing agent and to raise the manganese content in making steel

Other hyponyms of pig iron include basic iron, cinder pig, mine pig, spiegel iron, spiegeleisen.

pig iron (noun)	spiegel (noun)
crude iron tapped from a blast furnace	pig iron containing manganese; used as a deoxidizing agent and to raise the manganese content in making steel