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

https://wiki-cable.win/index.php/What_Makes_a_Slot_Interface_Feel_Clean_Instead_of_Cluttered%3F

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