He's talking about whether or not the game is provably fair.
For a lot of slots they are not provably fair but they are regulated by governments. So whether or not you trust that is up to you.
The same dice and slots can be provably fair man. You can easy count all probable outcomes in dice and slots and hash them to show later (big simplification of provably fair process). So even in such point of view there is no difference between them.