chief vs main

chief and main both are nouns.

Word	Noun	Adjective	Verb	Adverb
chief	Yes	Yes	No	No
main	Yes	Yes	No	No

As adjectives, chief and main are synonyms defined as:

Other synonyms of chief include master, primary, principal.

chief (noun)	main (noun)
a person who is in charge	a principal pipe in a system that distributes water or gas or electricity or that collects sewage
a person who exercises control over workers	any very large body of (salt) water
the head of a tribe or clan

chief (adjective)	main (adjective)
most important element	(of a clause) capable of standing syntactically alone as a complete sentence
	most important element
	of force; of the greatest possible intensity