wood coal vs lignite

wood coal and lignite both are nouns.

Word	Noun	Adjective	Verb	Adverb
wood coal	Yes	No	No	No
lignite	Yes	No	No	No

As nouns, wood coal and lignite are synonyms defined as:

Other synonyms of wood coal include brown coal.

wood coal (noun)	lignite (noun)
intermediate between peat and bituminous coal	intermediate between peat and bituminous coal
a carbonaceous material obtained by heating wood or other organic matter in the absence of air