labor union vs trade union

labor union and trade union both are nouns.

Word	Noun	Adjective	Verb	Adverb
labor union	Yes	No	No	No
trade union	Yes	No	No	No

As nouns, labor union and trade union are synonyms defined as:

labor union and trade union: an organization of employees formed to bargain with the employer

Other synonyms of labor union include brotherhood, trades union, union.

labor union (noun)	trade union (noun)
an organization of employees formed to bargain with the employer	an organization of employees formed to bargain with the employer