class action vs class-action suit

class action and class-action suit both are nouns.

Word	Noun	Adjective	Verb	Adverb
class action	Yes	No	No	No
class-action suit	Yes	No	No	No

As nouns, class action and class-action suit are synonyms defined as:

class action and class-action suit: a lawsuit brought by a representative member of a large group of people on behalf of all members of the group

class action (noun)	class-action suit (noun)
a lawsuit brought by a representative member of a large group of people on behalf of all members of the group	a lawsuit brought by a representative member of a large group of people on behalf of all members of the group