Yes. Orca and killer whale are two common names for the same animal, Orcinus orca. NOAA Fisheries notes that the killer whale is also known as orca and is the largest member of the dolphin family (Delphinidae)—an ocean apex predator found in every ocean.
The two names do not mark different species in everyday use. Scientists do recognize distinct killer whale populations and ecotypes (for example, fish-eating Residents and mammal-eating Transients in the North Pacific), but those groups are still discussed under the killer whale / orca label.
Source: NOAA Fisheries — Killer Whale