A casino operator runs the site and handles accounts, payments, and game...

https://sticky-wiki.win/index.php/Can_a_Slot%E2%80%99s_Theme_and_Sound_Make_It_Feel_Like_You%E2%80%99re_Due_a_Win%3F

A casino operator runs the site and handles accounts, payments, and game access. A slot provider makes the game. Provider names help you identify who built it and compare titles across catalogues