The Verification and Validation process areas are similar, but they address different issues. Validation demonstrates that the product, as provided (or as it will be provided), will fulfill its intended use, whereas Verification addresses whether the work product properly reflects the specified requirements. In other words, verification ensures that you built it right; whereas, validation ensures that you built the right thing. (from CMMI-Dev V1.3 Model)

Verification is a testing which ensures that the product and product components meets the requirement specifications (SRS). Successful verification is no guarantee that the product and product components will work in the real use case scenarios.

Validation is assurance that a product and product components meet the overall real use case scenarios as desired by the customer.