Again, this is true only if you are only looking at terrorism as a crime that needs to be prosecuted or making a moral judgement on it. From a moral standpoint, I agree it is no different if Al Qaeda takes an innocent hostage or if the government of Iran does the same thing. But when handling the situation, they are completely different. You can't prosecute an independent state the same way you can an individual or non-government entity. The State Department, CIA, FBI, UN and basically everyone else is going to have to handle the situation different so they are going to have different definitions of the word "terrorism" that are designed to suit their respective jobs. This all ties back to my original point, which if you remember isn't necessarily that states don't commit terrorism, but rather that the best you are going to end up with when attempting to define terrorism is a working definition that is built on your own ad hoc needs. Any attempt at a comprehensive definition is going to be either be A. full of holes, or B. too vague to be of any value.