spiegel vs spiegel iron

spiegel and spiegel iron both are nouns.

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

As nouns, spiegel and spiegel iron are synonyms defined as:

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

Other synonyms of spiegel include spiegeleisen.

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