Validation (process area)
Confirmation that the product, as provided (or as it will be provided), will fulfill its intended use. In other words, validation ensures that "you built the right thing." (See also "verification.")
Verification (process area)
Confirmation that work products properly reflect the requirements specified for them. In other words, verification ensures that "you built it right." (See also "validation.")
The establishment and maintenance of baselines and the identification of changes to baselines that make it possible to return to the previous baseline.