Often tapioca and sago are passed off as the same thing. They are not. The photo here shows pearl tapioca on the left which comes from a root crop like potato or yam. On the right, and much smaller, is sago which comes from the sago palm.
Seed tapioca looks exactly like and is the same size as sago, but it still is tapioca, though I've seen packets of it in supermarkets which say seed tapioca with sago in brackets--i.e. "seed tapioca [sago]", which is nonsense--if it looks like a duck and quacks like a duck it doesn't mean it is a duck--looks can be, and often are, deceiving.