well-known vs long-familiar

well-known and long-familiar both are adjectives.

Word	Noun	Adjective	Verb	Adverb
well-known	No	Yes	No	No
long-familiar	No	Yes	No	No

As adjectives, well-known and long-familiar are synonyms defined as:

well-known and long-familiar: frequently experienced; known closely or intimately

well-known (adjective)	long-familiar (adjective)
frequently experienced; known closely or intimately	frequently experienced; known closely or intimately
widely or fully known