Neckar River vs Neckar

Neckar River and Neckar both are nouns.

Word	Noun	Adjective	Verb	Adverb
Neckar River	Yes	No	No	No
Neckar	Yes	No	No	No

As nouns, Neckar River and Neckar are synonyms defined as:

Neckar River and Neckar: a river in Germany; rises in the Black Forest and flows north into the Rhine

Neckar River (noun)	Neckar (noun)
a river in Germany; rises in the Black Forest and flows north into the Rhine	a river in Germany; rises in the Black Forest and flows north into the Rhine