Answer:
Thematically, both often deal with the struggle of good over evil; Star wars is a great example of a story with both Sci-fi and fantasy characteristics (this combination is often called a 'space opera'), Star wars contains such classic fantasy elements as an 'evil emperor', a princess to save, and a chosen hero who defeats the dark lord. The only thing that separates this from typical examples of heroic fantasy is the setting, which includes Spaceflight and advanced technology.
Importantly, both genres, even at their most dissimilar provide a source of escapism from the mundaneness of modern and historical fiction (and non-fiction), by constructing a world, that never has, or never will be.