When I finish this race, I will have run a total of five miles. When I finish this race, I will have run a total of five miles. Why do we use present simple in the first sentence Although we're talking about action in the future

What is the difference? What is the difference between Ahmed works at a factory and Ahmed is working at a factory,please?

The first one It's my first note on italki.I want to improve my English and to make friends from all over the world also :). I can help anyone who would like to know or learn about my great language,Arabic.Thanks to everyone who will help me.