> I don’t live in Europe. Can I still enter?
Any person ages 13 through 19 anywhere in the world can enter.
> Is it okay to do more than one entry?
Yes, but remember that it is the quality of your work, not the quantity that will count.
> How is this different from the World Teenage Reporting Project showcase of climate champions?
This is a competition rather than a simple showcase under the aegis of the The Writing’s on the Wall project, and the bar is far higher. The profile subject’s successful impact is a vital factor. That success can be international, national or even something local that could easily be replicated widely to vastly magnify its impact. Unlike for that project, your story cannot have been published elsewhere.