km vs kilometer

km and kilometer both are nouns.

Word	Noun	Adjective	Verb	Adverb
km	Yes	No	No	No
kilometer	Yes	No	No	No

As nouns, km and kilometer are synonyms defined as:

km and kilometer: a metric unit of length equal to 1000 meters (or 0.621371 miles)

Other synonyms of km include kilometre, klick.

km (noun)	kilometer (noun)
a metric unit of length equal to 1000 meters (or 0.621371 miles)	a metric unit of length equal to 1000 meters (or 0.621371 miles)