What are the differences between wild, hatchery and farmed salmon?

Farmed Salmon
Farmed salmon do not reproduce naturally; farmed salmon do not migrate; farmed salmon are fed antibiotics because they are much more susceptible to disease and growth, and color enhancements (dye) turn the farmed salmon's grey flesh into the pink color found in natural fish.

Hatchery Salmon & Steelhead
Hatchery fish are generally spawned at the hatchery, reared and released on or off site. These fish do migrate to the ocean and back. However, conventional hatchery programs have the fish returning to the hatchery where they are taken for the next round of production. Programs known as "supplementation" are hatchery programs aimed at raising salmon for release in a controlled environment to get much higher juvenile survival rates, releasing the fish near high quality spawning grounds such that they "imprint" on the chemical signature of theses areas, migrate to the ocean and spawn naturally in the wild.