Answer:
Root Tubers are different than Stem Tubers. Root Tubers include: Dahlias, Sweet Potatoes (Kumara - Ipomaea battatas), Cassava and Jerusalem Artichoke (Helianthus tuberosus) Root Tubers are modified roots so do not have "eyes" (buds) like a Potato which is a. . . .
Stem Tubers include: Potatoes, New Zealand Yam or Oca (Oxalis tuberosa), Tuberous Begonias, Cyclamen, and Mignonette Vine (Anredera cordifolia) and they are modified stems so do have "eyes" (buds) which are axillary (side) buds and can become vegetative shoots.
Stem Tubers also generally go green (like a spud) if left in the light but Root Tubers generally don't (no chloroplasts in modified root.)