The difference in process and taste. According to the query food safety network shows:

1, soba is made from buckwheat ground into flour mixed with other flours to make pasta, while buckwheat hanging noodles is buckwheat dough after repeated kneading, stretching, to create a very fine filament-like noodles.

2, buckwheat noodles have a slightly grainy texture, there is a certain chewy, while buckwheat noodles eaten with a softer and more tender texture.