THE major difference is that, in other religions, violence shown by their "lunatic fringe" bring ringing denunciations almost immediately...
I heard MANY Christians condemning the abortion clinic bombings, even many on the pro-life side. If pagans started bombing places of worship of "People of the Book", you'ld see folks like myself, Broken Paw, and RevDisk out hunting the perpetrators. If a group of radical Jews started bombing mosques, I'd lay money that Rabbi would be loud and clear in his disgust of the act.
Yet Muslims, by and large, have ignored the violent acts of their lunatic fringe, even tacitly (and sometimes, not so tacitly) approved of it...
Most religions have used violence when it suited them. I'm not referring to hundreds of years ago. Ben-Gurion/Begin and the King David Hotel bombing. Both the Ulster nationalists and Catholics in Ireland. Heck, the Armenian Genocide was only about 90 years ago. Some have much higher body counts than others.
I suppose I'll be slated an Islamic apoligist, or an insensitive Islam hater, for my remarks, but hey, that's life. Islam is a religion, not a unified ethnic group. There are dozens of significant sects within Islam.
The group that we're more or less at war with is the Wahabbism. It was founded by Muhammad ibn Abd-al-Wahhab as a conservative 18th century reformist call of Sunni Islam. It is largely based on the teachings of Taqī ad-Dīn Abul Abbās Ahmad ibn 'Abd al-Halim ibn 'Abd as-Salam Ibn Taymiya al-Harrānī (yes, I copied that as there's no way I could ever memorize it), more universally known as Ibn Taymiyyah, about 1300. Ibn Taymiyyah really hated the infidels. Infidels primarily being Mongols, Sufism and Shia. Even today, for every one Westerner killed by Wahabbi fanatics, they kill at least a hundred Muslims of a different sect.
With me so far? The Wahabbi sect's main purpose is 'purifying' Islam at the point of the sword. This is primarily concerned with other Muslims as they wish to remove "heretical" beliefs from Islam, but also on the tangent of removing outside non-Muslim influences from the region. The Muslim Brotherhood has traditionally been the Wahabbi militant arm. There are other sects that are dangerous, but none are as remotely close to the Muslim Brotherhood and its derivatives.
If you want a cheat sheet that is woefully simplistic. The Shia are territorial. If they blow anything up, it'll be within a couple hundred miles of their own turf. They don't export terrorism from the region, 99% of the time. But they can cause a lot of issues in contested turf. Sunni are amoung the most industrially and educationally advanced, but also have the most militant sects. These sects ARE perfectly willing to travel to cause problems. Shia tends to have more people, Sunni tend to have the money. Druze, Alawite, Kurds, Albanians, et al, also territorial but their warfare ends to be ethnic. They don't have the land, people or money to compete with the Sunni and *expletive deleted*it.
If you're still skeptical, go find a soldier that served in the Balkans, Kurdistan, Turkey or Egypt if they were unduly concerned about the locals clipping them. Then go find another soldier that served in the Sunni triangle in Iraq, Yemen, et al.
Still with me?
If you are an American concerned with a hostile branch Islam, you only need to really worry about the militant arm of the Sunni. As none of the rest are gonna cross an ocean to bother you. If you're above average intelligence, you'll notice that the Sunni are heavily outnumbered by the other sects. An even more intelligence person would try to work ways to get these other sects to handle one's dirty work of removing the travelling Wahabbi sects.
As for those concerned about the lack of Muslim outrage, you shouldn't be. First off, there are plenty of Muslims outraged and very vocal about doing so. They don't get much space in media, whether in the US or in the ME. So go talk to them. Dearborn, MI has tons of 'em. Sure, they have their gripes about this or that, but they'll be honked off that idiots go around blowing stuff up. As for Muslims within the ME, the rank and file wisely keep very quiet about all matters. The tallest tree is cut down in very short order. Freedom of expression is not exactly common. Very real issues like corruption, ruling oligarchies, tightly controlled information, and state funded violence is rampant. There are lots of problems. Terrorism is a concern, but numerically speaking, not exactly the most important one at most times.