The theme is basically what the story is about. The...central topic. Not the events of the story or what happens in it, but what is is about. Something like coming of age, humans in conflict with technology, nostalgia, and the dangers of unchecked ambition (Macbeth is a good example of this one). The themes of life and death, grief, filial devotion, revenge, etc are central to Hamlet. A story might not have one theme; complex ones have many.

Mine, for example, deals with themes of prejudice, fear, loneliness, worthiness, ignorance, and love on varying levels. There's also the concept of the circular nature of history and humanity's tendency to be short-sighted in their decisions. In the end, the victory of the "good" guys is, at best, an abeyance of violence and a chance for the West to unite against the incursion of the East that is inevitably coming. So war will happen again despite everything my characters have done.

These are themes. Hope that helps.
-Quaddy

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