Max upload set to 800M in PHP, but Drupal only allowing 300M

The website is running Drupal 7.44 and lets users download large zip files of images and PDFs for product support.

PHP post and upload are both set to 800M but when I log into the Drupal Admin, the Thumbnail shows a max of 800M but the Downloadable file shows a max of 300M.

Is this a Drupal limitation?


Drupal version: