PokerStars is a poker company that happens to have a casino. That's the cleanest way to describe what you find when you land on the site. The whole front door is pure poker. Spade logo, Download PokerStars, Play in Browser, everything built around getting you into a tournament or a cash game.
Casino exists as a single word in the top navigation, wedged between Poker and Sports. Click it and you end up in something that feels like a separate product that happens to share your login. Different layout, different rhythm, different priorities.
This matters if you're signing up specifically for slots or live dealer. You're not walking into a casino that also runs poker. You're entering the side door of a poker house. The casino is real, stocked, and operated seriously, but it grew up in the shadow of the poker platform and you can feel that the moment you start clicking around.