Balance training equipment and yoga props both support body control, but they do it in different ways. Balance equipment usually creates instability or a narrower base of support. Yoga props usually make a pose more accessible, supported, aligned, or comfortable.
The difference matters because a block, strap, bolster, or blanket is not meant to wobble the user. A balance board, pad, or disc is meant to challenge control. Both can belong in a thoughtful routine, but they should not be used as if they solve the same problem.