"What's the difference?" you might ask. Radical has a a few different connotations. In a general sense it means to go to the root or source of a thing. In a political sense it means to favor extreme measures in order to implement political change. The word can also mean an extreme departure from the usual or traditional. So in what sense does this apply to Islamic jihadists?
In the media and in popular culture the assumption is that these islamic radicals represent a depature from good and true Islam. They are an abberation or a mutation of the reiligion, much like other religions who's adherents take things too far, and so depart from the good and true faith. So the media and the public at large ar using the term radical as an extreme departure from the usual or traditional observance of Islam. The question is, "Is this really the case?"
The word fundemental means the original or generating source of something. It is something of central importance, or the originating source of something. In this last sense it can be a substitute for the word radical. However, a fundementalist a person who subscribes to fundamentalism in their chosen religion. It is a person who is working to maintain or recover the original tennants of their religion.
I know this because I am a fundamentalist. This word has fallen into disrepute because the enemies of my particular faith have lebeled it a bad thing. It simply means that I want to return to and maintain the original intent and foundation of my faith as put forth in the Bible. I do not favor radical or extreme measures to force this fundamentalsim on others. I believe that if the Bible is true and properly understood in its original intent that people will naturally want to follow it. If they don't see it, "As for me and my house, we will serve the LORD." I do have dedication to my faith in that I would die for my beliefs, and I would lay down my life for others in the pursuit of my faith. The one thing I would never do is intentionally cause harm to another as this is a fundemental tenant of my faith, "to love my neighbor as myself."
The fundamental Islamists have the same dedication and devotion to Islam as I do to the Bible. In their case they would murder or die for their faith. An idiom that they use commonly use towards their enemies is that they, "love death more than we love life." They are radical in the sense that they favor extreme measures in order to implement political change, and they are fundemental in that what they advocate is not an extreme form of Islam that is a radical departure from the faith, but a fundamental form of Islam that is literally taken from the Koran.
There is a myth in the minds of Americans and many in the West that there is a moderate form of Islam. This is a lie, as the muslim Imams say there is no moderate or extreme Islam, there is only Islam. All muslims are called to jihad (holy war). Jihad is waged on many levels starting with words of peace and friendship, but ending with acts of war and desturuction for the infadel (backslidden muslims and those of any other faith). This is Islamic fundementalism, the only kind of Islam that matters to the leaders in the faith because it is true Islam. To hear it straight form the source watch the video below: