riser vs structural member

riser and structural member both are nouns.

Word	Noun	Adjective	Verb	Adverb
riser	Yes	No	No	No
structural member	Yes	No	No	No

As nouns, structural member is a hypernym of riser; that is, structural member is a word with a broader meaning than riser:

riser: structural member consisting of the vertical part of a stair or step
structural member: support that is a constituent part of any structure or building

riser (noun)	structural member (noun)
structural member consisting of the vertical part of a stair or step	support that is a constituent part of any structure or building
a vertical pipe in a building
a person who rises (especially from bed)