how about this: Hasblo figures were mass produced. and if you look at one of their Han figures the head sculpt is exactly the same as all their Han figures.
sideshow makes their figures in a "Limited" capacity. usually not more than a couple thousand. everyone talks bad on their little flaws and mistakes but if you compare a Plo Koon Sideshow figure next to a Hasblo Plo Koon im pretty sure you'll notice a difference. and another thing...with sideshow you get a hell of a lot more accessories like: the actual pouches on their belt, 2 lightsabers, the small items that go into the pouches, a usually a set of extra hands, and whatever exclusive item they might come with. what comes with a Hasblo other than say the weapon?? (seriously, i dont know)