efficiency expert vs efficiency engineer

efficiency expert and efficiency engineer both are nouns.

Word	Noun	Adjective	Verb	Adverb
efficiency expert	Yes	No	No	No
efficiency engineer	Yes	No	No	No

As nouns, efficiency expert and efficiency engineer are synonyms defined as:

efficiency expert and efficiency engineer: an expert in increasing the efficient use of machines and personnel

efficiency expert (noun)	efficiency engineer (noun)
an expert in increasing the efficient use of machines and personnel	an expert in increasing the efficient use of machines and personnel