subordinating conjunction vs subordinate conjunction

subordinating conjunction and subordinate conjunction both are nouns.

Word	Noun	Adjective	Verb	Adverb
subordinating conjunction	Yes	No	No	No
subordinate conjunction	Yes	No	No	No

As nouns, subordinating conjunction and subordinate conjunction are synonyms defined as:

subordinating conjunction and subordinate conjunction: a conjunction (like `since' or `that' or `who') that introduces a dependent clause

subordinating conjunction (noun)	subordinate conjunction (noun)
a conjunction (like `since' or `that' or `who') that introduces a dependent clause	a conjunction (like `since' or `that' or `who') that introduces a dependent clause
the subordination that occurs when a conjunction makes one linguistic unit a constituent of another