koine vs interlanguage

koine and interlanguage both are nouns.

Word	Noun	Adjective	Verb	Adverb
koine	Yes	No	No	No
interlanguage	Yes	No	No	No

As nouns, koine and interlanguage are synonyms defined as:

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

Other synonyms of koine include lingua franca.

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