timber vs building material

timber and building material both are nouns.

Word	Noun	Adjective	Verb	Adverb
timber	Yes	No	No	No
building material	Yes	No	No	No

As nouns, building material is a hypernym of timber; that is, building material is a word with a broader meaning than timber:

timber (noun)	building material (noun)
a beam made of wood	material used for constructing buildings
a post made of wood
(music) the distinctive property of a complex sound (a voice or noise or musical sound)
land that is covered with trees and shrubs
the wood of trees cut and prepared for use as building material