Is fusion summon the same as special summon?

A Fusion Summon is a Special Summon and things that can be used against Special Summons can also be used against a Fusion Summon.

But not all Special Summons are Fusion Summons, even if they do so happen to summon a Fusion Monster. For example, Cyber Stein Special Summons a fusion monster, it does not Fusion Summon it.