What's the difference between freedom fighters and terrorists?

One man's terrorist is other man's freedom fighter.
- Gerald Seymour

Here is what Noam Chomsky said in one of his lecture.  I am paraphrasing it.

Every word in linguistic has two meanings. One is the theoretical meaning and other the technical meaning.

The theoretical meaning is the one which is always kept on papers and are used in non-practical work. The technical meaning is the meaning the word has in practical real world application.

Example:

Democracy - 

Theoretical meaning : Democracy is government by the people, of the people and with the people

Practical meaning :Democracy is a government in which is run by vote bank politics. India is a best example

Peace Process -

Theoretical meaning : The attempt to create peace using non violence mode.

Practical meaning : The US on-going in Middle East is called peace process.

Considering USA as a example, it  has already decided that whatever it does in middle east is a peace process and whatever the middle-east people do is terrorism. This is a non falsifiable hypothesis. It cannot be refuted because it will produce contradictions.

So, by definition the act of USA is a peace process. No amount of argument can make it terrorist act. On the same logic, whatever Iraq does is by definition terrorism, no matter how hard they try to convey there message, it will still be called terrorism.