It used to be the case that the thumbnail of your project is also the primary picture that appears on the project page. This meant three things:
- You can’t choose different pictures for your thumbnail and the primary picture.
- The primary picture always appears between the title and the first paragraph of the page.
- You can’t edit the size of your primary picture.
Now, setting the thumbnail is separate from picking the primary picture of your page. This gives you better control over your page content.