An archetype is a pattern of a recurring symbol, story, or character, whereas the theme is the central idea. Archetype is something to base your story around, something that happened in the past and stood the test of time as something universal. On the other hand theme draws from the archetype but it is not limited to it. Themes can be contemporary and based around the archetype. For example, we can have modern day Romeo and Juliet, based around the archetype of the immposible love.
