E-Commerce specialty stores and subscriptions usually disallow VISA, MasterCard, and American Express gift cards because it can allow a consumer to dodge a continuity sales model.
If your debit card or savings card does not have a cardholder name or a billing address, it cannot be used to purchase anything online as these are two of several important components to an online transaction.
Yes. The purpose of a VISA Debit Gift Card is to disassociate the source of the money. VISA Debit Gift Cards may have a certain limit set to its funds before its expiration, or it may not be able to be charged. Most vendors online will disallow this type of card to be used in a transaction because you would essentially be able to legitimately pay any upfront costs, yet when the vendor, hypothetically, attempts to charge you again, they may be left with a loss as the gift card is not tied to any bank account or credit account.
The VISA Debit Gift Card is a gift card — the other type of card referenced is a type of debit card probably meant to teach minors the values of saving and spending money.