positive reinforcer vs positive reinforcing stimulus

positive reinforcer and positive reinforcing stimulus both are nouns.

Word	Noun	Adjective	Verb	Adverb
positive reinforcer	Yes	No	No	No
positive reinforcing stimulus	Yes	No	No	No

As nouns, positive reinforcer and positive reinforcing stimulus are synonyms defined as:

positive reinforcer and positive reinforcing stimulus: a reinforcing stimulus that serves to increase the likelihood of the response that produces it

positive reinforcer (noun)	positive reinforcing stimulus (noun)
a reinforcing stimulus that serves to increase the likelihood of the response that produces it	a reinforcing stimulus that serves to increase the likelihood of the response that produces it