Ask HN: What's the difference between ICO and selling shares?

I've not been following the coin hype too closely, but cursorily, it looks like an ICO (like, for example, the XRP from Ripple) is no different than a company issuing shares. The latter, of course, is heavily regulated; but there's nothing regulating the former.

So: is there a difference between the two? I'd love to know.