mystery play vs dramatic play

mystery play and dramatic play both are nouns.

Word	Noun	Adjective	Verb	Adverb
mystery play	Yes	No	No	No
dramatic play	Yes	No	No	No

As nouns, dramatic play is a hypernym of mystery play; that is, dramatic play is a word with a broader meaning than mystery play:

mystery play: a medieval play representing episodes from the life of Christ
dramatic play: a dramatic work intended for performance by actors on a stage

Other hypernyms of mystery play include drama, play.

mystery play (noun)	dramatic play (noun)
a medieval play representing episodes from the life of Christ	a dramatic work intended for performance by actors on a stage