koine vs lingua franca

koine and lingua franca both are nouns.

Word	Noun	Adjective	Verb	Adverb
koine	Yes	No	No	No
lingua franca	Yes	No	No	No

As nouns, koine and lingua franca are synonyms defined as:

koine and lingua franca: a common language used by speakers of different languages

Other synonyms of koine include interlanguage.

koine (noun)	lingua franca (noun)
a common language used by speakers of different languages	a common language used by speakers of different languages