When I googled, I only find the difference in features/concepts. I'm actually referring to the content in the document when filing provisional vs. non-provisional. How is the literature different?
The primary difference is the lack of formality requirements in filing a provisional application. Provisionals do not require claims or proper drawings that comply with the standards.
On the other hand, if the contents of a provisional do become important, the substance of the content will be scrutinized just as strictly as it would be for a non-provisional.