A casino operator runs the site where you browse and play, while a slot...

https://fernandosmastercolumns.swiftnestly.com/posts/why-do-some-slot-symbols-look-blurry-on-mobile

A casino operator runs the site where you browse and play, while a slot provider makes the game itself. Provider names matter in a catalogue because they help you identify who created a slot and find other games from the same studio