Western/Christian Extremists = Far right nut jobs who shout in people's faces and use offensive ignorant banners at worst they have the odd ultra loner nut job who actually uses terrorism to further his goals.
Islamic Extremists = Reguarly plant bombs in civilian populations, Reguarly go on shooting sprees, Reguarly cut people's heads of with blunt knives I could go on...
People say oh but there are extremists in every culture, yes that's true but there are far, far more of them in Islam and they are fare more extreme. The far right is a problem but it's a problem that pales in significance compared to the issue of Islamic extremism.