easy going vs plain sailing

easy going and plain sailing both are nouns.

Word	Noun	Adjective	Verb	Adverb
easy going	Yes	No	No	No
plain sailing	Yes	No	No	No

As nouns, easy going and plain sailing are synonyms defined as:

Other synonyms of easy going include clear sailing.

easy going (noun)	plain sailing (noun)
easy unobstructed progress	easy unobstructed progress