throwing board vs spear thrower

throwing board and spear thrower both are nouns.

Word	Noun	Adjective	Verb	Adverb
throwing board	Yes	No	No	No
spear thrower	Yes	No	No	No

As nouns, throwing board and spear thrower are synonyms defined as:

throwing board and spear thrower: a device resembling a sling that is used in various primitive societies to propel a dart or spear

Other synonyms of throwing board include dart thrower, throwing stick.

throwing board (noun)	spear thrower (noun)
a device resembling a sling that is used in various primitive societies to propel a dart or spear	a device resembling a sling that is used in various primitive societies to propel a dart or spear