The above post offers some really good, practical advice on how to think about this paper. To give you some more ideas you might consider writing about how your hobbies differed from country to country (if they do). You might also think about what would be most interesting for an audience of your peers. 

What would your friends want to know about how these two countries differ, how they're the same? 

Once you have your topics picked out, you can write your body paragraphs narrating your experience with specific examples. When you've finished your body paragraphs, you can go back and write an introduction.  

If I understood this correctly, it seems that you've lived in both places, so keep it simple. Pick a handful of criteria to compare. For instance, you might think about weather (that ought to be easy enough), food, school, or other aspects of everyday life. If you only have a little while to write this, these types of topics would require little research, and they would be drawn from your personal experiences, which should be pretty easy.