binder board vs binder's board

binder board and binder's board both are nouns.

Word	Noun	Adjective	Verb	Adverb
binder board	Yes	No	No	No
binder's board	Yes	No	No	No

As nouns, binder board and binder's board are synonyms defined as:

binder board and binder's board: a cardboard used by bookbinders to make covers for books

binder board (noun)	binder's board (noun)
a cardboard used by bookbinders to make covers for books	a cardboard used by bookbinders to make covers for books