Are Polar Bears more dangerous than Grizzly Bears?

Yes-

Polar Bears are hunters by nature, and are one of the rare animal species that will look to kill humans for food! Of course this is limited to young adult bears, and ones who aren't able to access their natural food source.

Grizzly Bears have been known to attack humans, but thats because of human stupidity! When I say human stupidity, I mean humans getting too close to the cubs, humans trying to take a selfie with a grizzly, and unknowingly getting in between a grizzly and its prey. Grizzlies DONT hunt humans for food, they aren't out there seeking to kill humans to eat, that is the key difference.

Both are just as bad, but polar bear environment, they get hungry often and may opportunistically go after a human for food.

Yes they are. A polar bear will eat people, but a Grizzly seldom see people as prey unless it has been injured and and is starving. People who live in polar bear country has to bear-proof their houses.