Is orca faster than blue whale?

Yes, but not by much. The fastest a Blue Whale can go is approximately 50 km/h (about 30 mph). The fastest a Killer Whale, or an Orca, can go is approximately 56 km/h (about 35 mph). But, you got to remember: Killer Whales, or Orcas, aren't actually whales at all, but a specific genus of dolphin.