tracer vs tracer bullet

tracer and tracer bullet both are nouns.

Word	Noun	Adjective	Verb	Adverb
tracer	Yes	No	No	No
tracer bullet	Yes	No	No	No

As nouns, tracer and tracer bullet are synonyms defined as:

tracer and tracer bullet: ammunition whose flight can be observed by a trail of smoke

tracer (noun)	tracer bullet (noun)
ammunition whose flight can be observed by a trail of smoke	ammunition whose flight can be observed by a trail of smoke
(radiology) any radioactive isotope introduced into the body to study metabolism or other biological processes
an instrument used to make tracings
an investigator who is employed to find missing persons or missing goods