radio theatre vs radio theater

radio theatre and radio theater both are nouns.

Word	Noun	Adjective	Verb	Adverb
radio theatre	Yes	No	No	No
radio theater	Yes	No	No	No

As nouns, radio theatre and radio theater are synonyms defined as:

radio theatre and radio theater: a dramatized, purely acoustic performance, broadcast on radio or published on audio media, such as tape or CD.

Other synonyms of radio theatre include audio drama, radio drama.

radio theatre (noun)	radio theater (noun)
a dramatized, purely acoustic performance, broadcast on radio or published on audio media, such as tape or CD.	a dramatized, purely acoustic performance, broadcast on radio or published on audio media, such as tape or CD.