The main difference between a play written in verse and one written in narrative prose is the use of poetic elements such as line breaks and rhyming in verse, while narrative prose does not have these poetic features. In verse, the text is structured in a rhythmic pattern with line breaks and often contains rhymes, creating a more musical and poetic form of expression. Narrative prose, on the other hand, is written in a straightforward, linear style without the use of poetic devices, focusing more on the narrative and storytelling aspects of the text.