Pilot
A test implementation of a service with a limited scope in a live environment. A pilot usually deploys to a small group of users to validate the service before full rollout.
Impact
Pilots reduce the "blast radius" of failure. If it breaks, it only breaks for a few.
Weinto take
We prefer Canary Releases over Pilots. A pilot implies a manual "phase." A canary release is an automated percentage rollout (1% -> 5% -> 100%) controlled by traffic management. Same goal, better technology.