Validation: Are we building the right product?
According to the Capability Maturity Model (CMMI-SW v1.1),
Software Verification: The process of evaluating software to determine whether the products of a given development phase satisfy the conditions imposed at the start of that phase. [IEEE-STD-610]
Software Validation: The process of evaluating software during or at the end of the development process to determine whether it satisfies specified requirements.