starter motor vs starting motor

starter motor and starting motor both are nouns.

Word	Noun	Adjective	Verb	Adverb
starter motor	Yes	No	No	No
starting motor	Yes	No	No	No

As nouns, starter motor and starting motor are synonyms defined as:

starter motor and starting motor: an electric motor for starting an engine

Other synonyms of starter motor include starter.

starter motor (noun)	starting motor (noun)
an electric motor for starting an engine	an electric motor for starting an engine