non-slave vs slaveless

non-slave and slaveless both are adjectives.

Word	Noun	Adjective	Verb	Adverb
non-slave	No	Yes	No	No
slaveless	No	Yes	No	No

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

Other synonyms of non-slave include free-soil.

non-slave (adjective)	slaveless (adjective)
where slavery was prohibited	where slavery was prohibited