The difference between the two is just marketing and time. Glass's success crucially depends on convincing normal people that they won't look like dorks wearing it. It doesn't matter if it's a million times better than Xybernaut, if you can't get normal people to feel normal wearing it, it won't succeed. A million times better isn't good enough if it's still worse than not wearing it.

Technologists have always thought the problem with wearable computing was that the technology wasn't good enough. Nowadays, I think the real problem with wearable computing is fashion.