Validation is the checking of data before processing to ensure that it is acceptable for it or not. E.g. When entering a date, the validation for month is 1-12, you cannot enter 13, its out of range. Similarly a telephone number cannot contain letters.
Verification is the checking of data that has been copied from one place to another to ensure that is replaces the original one. E.g. PASSWORD. When you sign up in a site, just like WIKIANSWERS, you have to enter your password twice, the second entry being compared with the first.
Example in an a paper if a teacher asks us to cross xheck thats validation and when the teacher checks it again orr a re-check thats verification