Answer 1

Data validation: making sure that the data has the correct format. For example, in the case of a form, sometimes you want a field to not be empty, or another to be a number. In the case of an email, this would be checking that the email actually looks like an email ([e-mail]).

Email verification: making sure the email address exists and belongs to the user who submitted it. This is usually done by generating a temporary, one-use link to the site and sending an email asking the user to either click that link to complete the registration or ignore the mail if the email belongs to someone else.

However, since you do verifications (in the broad sense of the term) when doing validations, you can expect verification to be used in place of validation sometimes. If someone speaks of form verification for example, they actually mean validation.