Verification: The main requirement for verification are documents like business requirement speculations, system requirement specifications, high level requirements, use cases, reference web sites etc. . Meetings are conducted or the documents are reviewed to check whether the product is fulfilling the clients’ requirements. Verification always takes place before validation and it is also known as Quality Assurance.
Validation: The main requirement for validation is the product itself. The product is tested to check whether it has fulfilling all requirements, as specified in the documents. The testing conducted can be any of Black Box, White Box or Experience based testing. Validation takes place only after coding is done or after a product can be executed. Validation is also known as Quality Control.