radar vs radio detection and ranging

radar and radio detection and ranging both are nouns.

Word	Noun	Adjective	Verb	Adverb
radar	Yes	No	No	No
radio detection and ranging	Yes	No	No	No

As nouns, radar and radio detection and ranging are synonyms defined as:

radar and radio detection and ranging: measuring instrument in which the echo of a pulse of microwave radiation is used to detect and locate distant objects

Other synonyms of radar include microwave radar, radiolocation.

radar (noun)	radio detection and ranging (noun)
measuring instrument in which the echo of a pulse of microwave radiation is used to detect and locate distant objects	measuring instrument in which the echo of a pulse of microwave radiation is used to detect and locate distant objects