bronchus vs bronchial tube

bronchus and bronchial tube both are nouns.

Word	Noun	Adjective	Verb	Adverb
bronchus	Yes	No	No	No
bronchial tube	Yes	No	No	No

As nouns, bronchus and bronchial tube are synonyms defined as:

bronchus and bronchial tube: either of the two main branches of the trachea

bronchus (noun)	bronchial tube (noun)
either of the two main branches of the trachea	either of the two main branches of the trachea