balsa wood vs wood

balsa wood and wood both are nouns.

Word	Noun	Adjective	Verb	Adverb
balsa wood	Yes	No	No	No
wood	Yes	No	No	No

As nouns, wood is a hypernym of balsa wood; that is, wood is a word with a broader meaning than balsa wood:

balsa wood: strong lightweight wood of the balsa tree used especially for floats
wood: the hard fibrous lignified substance under the bark of trees

balsa wood (noun)	wood (noun)
strong lightweight wood of the balsa tree used especially for floats	any wind instrument other than the brass instruments
	a golf club with a long shaft used to hit long shots; originally made with a wooden head
	the trees and other plants in a large densely wooded area
	the hard fibrous lignified substance under the bark of trees