One simple way that they differ is that while people with migraine can generally go lay down in some helpful situation (dark, quiet room, damp cloth on forehead, etc.), people with to CH are too agitated to do that (and it doesn't help the pain). Agitation -- pacing, rocking, etc. -- is a clinical sign of CH. This is pretty generally true, even in milder versions of CH. Since you say that in some situations it your attacks can last for a while, maybe you have experience. At the most basic level, medical preventives and abortives for CH and migraine are the same, so it might not matter all that much. O2, however, is generally not effective for migraine. The D3 regimen is a preventive that helps with both.