non-slave vs free-soil

non-slave and free-soil both are adjectives.

Word	Noun	Adjective	Verb	Adverb
non-slave	No	Yes	No	No
free-soil	No	Yes	No	No

As adjectives, non-slave and free-soil are synonyms defined as:

Other synonyms of non-slave include slaveless.

non-slave (adjective)	free-soil (adjective)
where slavery was prohibited	where slavery was prohibited