Ask ten people to write a true-to-life description of an event they all witnessed together and you’ll get ten totally different descriptions for the following reasons:

1. People see things differently and that different perspective results in a different way of writing. Which is style.
2. When those people sit down to write, their personalities, background — everything that makes them who and what they are — kicks in and influences how they describe what they just saw. And that, too, is style.
3. Add in everything else that makes a person the kind of person he/she is and you have a totally unique writing style for each and every person on the planet.