Explain how you are different from others in your field. People may not be able to tell just from looking at your website. Most people are out there copying everyone else, trying to look like everyone else. Pointing out your differences is a much more interesting read in terms of social media content.
And two points to keep in mind with this:
1 - You don't have to put other people down to do this. It does not have to be "Why those other guys suck."
2 - It does not have to be a big difference. It could be something unique about your past experience. It could be a slightly different perspective you have. If you are a musician, it could be an aspect of your pre-show routine. If you are a business person, it could be what you like to read in your spare time. It all helps people get to know you a little better.