spiegel iron vs spiegeleisen

spiegel iron and spiegeleisen both are nouns.

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

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

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

Other synonyms of spiegel iron include spiegel.

spiegel iron (noun)	spiegeleisen (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