Though any grape can in theory be eaten out of hand, some may be so tart that you won’t want to. Tarter ones are used for wine; sweeter ones are generally preferred as Table Grapes. Some grapes that would make reasonable Table Grapes — such as the Concord — aren’t sold as Table Grapes, because they don’t survive shipping well: they are used for processing into preserves and juices instead. And others that used to be considered good Table Grapes, such as the Black Monukka grape, aren’t considered that good any more, because being older grape varieties they have seeds in them.
In California, Table Grapes are likely to be packed into boxes right in the field. In Australia or South Africa, they are more likely to be harvested, collected, brought into sheds and then packaged there.