Yangtze vs Changjiang

Yangtze and Changjiang both are nouns.

Word	Noun	Adjective	Verb	Adverb
Yangtze	Yes	No	No	No
Changjiang	Yes	No	No	No

As nouns, Yangtze and Changjiang are synonyms defined as:

Yangtze and Changjiang: the longest river of Asia; flows eastward from Tibet into the East China Sea near Shanghai

Other synonyms of Yangtze include Chang, Chang Jiang, Yangtze Kiang, Yangtze River.

Yangtze (noun)	Changjiang (noun)
the longest river of Asia; flows eastward from Tibet into the East China Sea near Shanghai	the longest river of Asia; flows eastward from Tibet into the East China Sea near Shanghai