unlearned vs unlettered

unlearned and unlettered both are adjectives.

Word	Noun	Adjective	Verb	Adverb
unlearned	No	Yes	No	No
unlettered	No	Yes	No	No

As adjectives, unlearned and unlettered are synonyms defined as:

unlearned and unlettered: uneducated in general; lacking knowledge or sophistication

Other synonyms of unlearned include ignorant, nescient.

unlearned (adjective)	unlettered (adjective)
not established by conditioning or learning	having little acquaintance with writing
uneducated in general; lacking knowledge or sophistication	uneducated in general; lacking knowledge or sophistication
not well learned