'not verified' means that we have not yet verified that the person behind that card is in fact who they say they are. We do that by sending a verification email to the person's inbox.
An unverified card is not registered to a Haystack account. Anyone can edit the basic details on that card. However only the owner of a card can add or remove gallery images and some social links.

Verified cards belong to a person with a Haystack account who has verified they own the Haystack card. Once a Haystack card has been verified, only the owner can edit its details.