More vicious and dangerous, no. Smarter, better prepared and more adept as a pack hunter, yes. I think that equating one species' ability to kill the other with higher levels of viciousness and danger is the wrong way to look at this. I think it has more to do with the the fact that one combatant is a solitary, self-taught hunter with a brain that weighs 34 grams while the other is a specialty hunter taught the tricks of the trade since birth using a complex system of linguistics and passed down pack knowledge with a brain that weighs 5,600 grams.
Yes, killer whales are among the deadliest predators. They are large and powerful creatures programmed to kill their prey. They spend their time seeking prey and are large enough to take very large creatures like sharks, octopus and smaller whales. They kill with great precision and their huge jaws kill instantly.
Killer whales use coordinated tactics and deadly precision to kill their prey, but in spite of the organized manner in which they hunt, they are still not as deadly as the planet's apex predator on both land and sea. Humans are deadlier than killer whales not only in how they kill but, in the sheer scale and volume of what they kill.
Killer Whales is not the deadliest predator. Killer Whales are known to attack humans on rare occasions. Killer Whales don't eat people or generally try to attack them. Whether it’s because we don’t resemble any food sources they would normally eat or we just don’t taste appetizing to them is unknown however killer whales don’t appear to have a desire to hunt and/or eat us, and that’s definitely a good thing.
Unlike sharks killer whales don’t typically attack humans unless they feel threatened and in no known cases has a human ever been eaten by a killer whale.
For the most part killer whales are actually considered to be very friendly animals, at least as far as we know and have experienced them to be.