How is the Tarot related to other forms of divination?
Basically, it ain’t. Historically, at least. But many people who have some skill in one of these other arts have sometimes tried to find correspondences between them and the Tarot. Of the people I’ve talked to who are skilled in runes/astrology/i ching/etc., most of them wish the people who made such decks wouldn’t bother. But, some people like them. If you’re already familiar with one of these other systems of divination and wish to study the Tarot as well, it may be a worthwhile ‘shortcut’ to pick one of these decks. For a novice, it is probably more confusing than it needs to be.