Let's say, "not in reality, but in spirit".
The major differences between Islamism and Totalitarianism are organizational. The totalitarian organization tends to center power totally in the Leader. Hitler or Stalin were not only the supreme authority, as in tyranny, but actually had the only real power in their states. Arendt recognized that offices in totalitarian states tend to be multiplied, so that none can gain any real strength. Ultimately, all decisions come from the Leader alone. So, paradoxically, totalitarian states are over-organized, but power is so diffused between various offices as to be meaningless. Even the secret police, a locus of power, have no real authority because they are no longer investigating crimes- they are waiting to be told by the Leader who to arrest.
It is hard to see any similarity in the organization of most terrorist groups. Osama bin Laden might be the leader, but there is little to suggest that he rules al-Quaida by fear and intimidation. Also, while he commands a certain amount of loyalty, it is far less than what is commanded by various religious figures, including of course, God himself. The Totalitarian Leader cannot allow for God to exist in fact or possibility as anything but a tool. On the other hand, it could be said that most millenarian groups hope to establish God as a supreme Leader, in a totalitarian model, on Earth, a hope that might drive their actions.
The most important difference then is that Islamists don't control the apparatus of a state. This seems slight, but otherwise it's like calling them 'monarchalists'- they might be, but this means little without a monarchical state. Saddam Hussein could be considered a totalitarian leader, and actually modelled himself after Stalin. But, he was also a secular leader, for exactly the reason noted above. The people cannot even have the hope of God under totalitarianism.
Balint notes that although there is "an underlying identity of state tyranny and nonstate terrorism, it is also true that al-Quaida terrorists, for instance, do not control a state apparatus- despite their aspiration to form a global sharia-based caliphate."
Balint notes that 'totalitarian tendencies' have survived, and this is what I call totalitarianism in spirit. It might be safe to call Islamism, and in fact all religious fundamentalisms, as totalitarian ideologies. Similarly, totalitarian political ideolodies, such as Nazism or Communism, tended to sharply resemble religious belief.
At the heart of every totalitarian ideology is a single belief that cannot be questioned. The power of this single belief, really just an idea, is that it seems to explain a great deal about existence. So, for the Nazis, the race idea explains everything to do with human societies and civilizations. In state communism, dialectical materialism does the same; everything else is superstructure. In both cases, the idea explains what has happened and what will happen in the future. In both cases, it describes processes that are not visible to the senses.
The case of religious eschatology is actually identical to this simply because Nazism and Communism were secular eschatologies. Again we have an idea, God, that explains everything that has happened and that will happen. Again we have an idealized future which seems to justify anything that brings said future about. Instead of "the end of history" or "the death of the inferior races" we have, essentially, the Rapture. Again, the idea makes concern for one's fellow beings seem rather trite.
The idea seems to explain everything, and soon finds that it has to oppose anything that it cannot explain. The totalitarian ideology is itself totalizing- claiming to explain everything, it cannot tolerate counter-information. Instead of a belief, it becomes a belief system. When the Islamist theorist Sayid Qutb wrote that "this struggle is... an eternal state, because truth and falsehood cannot coexist on this earth,"he echoes the totalitarian idea that nothing can exist which is against The Single Truth- be it the dialectic, or the 'survival of the fittest'. This is also why jihadists seek essentially to destroy cultures that they come in contact with- not to convert them. For the same reason as Nazism had to destroy the Jews, and would have had to destroy various other groups, and Communism had to build the gulags- the march of the 'forces' behind history cannot be slowed down by humans. As Marx wrote, the bourgeois has sewn the seeds of his own destruction- he has put himself against the march of history.
What both Nazism and Communism got from Hegel was this idea of history as the embodiment of subjective ideas and as the march of inexorable forces.But, Hegel gets this from Christian theology, and hence it replicates the idea of the fall of man and his ultimate redemption in the End Times. Religious fanatics think the same way because they got there first basically.
This inexorable march gave Nazism and Communism their unreal nature- they spent a fortune on corpse-factories, for example. Often, they were not pragmatic. This also gives Islamism an unreal character. It is not pragmatic at all. Arendt writes that totalitarian ideologies have a "supreme disregard for immediate consequences,... disregard of national interests, contempt for utilitarian motives, and unwavering faith in an ideological fictitious world." (417) One can hardly imagine a better description of the mindset behind suicide bombings. The point isn't to establish the caliphate, so much as to prove one's devotion to the ideology.
Therefore, most totalitarian beliefs are not well-made for state rule. They rely on constant movement, and stagnate as they become the "establishment'- they are inherently radical. The avant garde cannot become the old guard. This is why both Communism and Nazism treated their home country as a sort of base for world conquest. Hitler treated Germany like a stepping stone- what was important was whatever was good for Nazism. Notice that the point of jihad seems to be in the jihad itself- in other words, it is war waged not to conquer so much as simply to continue waging the war.
The appeal therefore of totalitarianisms is that they allow bored and atomized people in modern society an opportunity to become part of a forward-moving wrecking machine. However, without a state apparatus, it's not clear that Islamism will, or can, endure. These beliefs tend to lead to deep cynicism, especially the further they are from reality. The caliphate will not return, and the people who are fighting for it have proven by dying only that they are mortal- not the direction of history.
Moreover, it makes no sense to fight 'Islamism' in the same way that the cold war was fought- as a war against states. The reason that the War on Terror is failing is because it fundamentally understands the mindset of its opponents, but not their conditions, nor how to fight non-state totalitarians. The hawks want to fight the Cold War against guerrillas.
Arendt felt that totalitarianism could well return, and had ideas on how to fight it. She suggested fighting against social alienation and atomization- incorporating people into the community so that they would want to preserve it. Interestingly, and I'm disappointed that Balint doesn't mention this, she warned strongly against replacing Natural Law theory with the idea that rights are state-given, and hence 'stateless people' are only given rights by an act of benificence on the part of a state. In other words, the idea that the Geneva Conventions, habaes corpus, and the right to a fair trial don't apply to 'non-state actors' is itself a dangerous idea because it separates certain people from humanity regardless of their actions- refugees for instance, or 'illegal aliens' lose any innate 'human rights'. She warned that this can necessitate a second legal system, outside of the normal legal system, and a system of camps. When certain people can be defined as not having any innate rights, they can eventually be removed from the world of the living, even while alive. They can be lost down memory holes of total control.
Certainly, Balint is right that the Islamists pose more of a totalitarian threat than the people fighting them. Even if they have more state resources, The Warriors Against Terror (TWAT) are authoritarians- not totalitarians, and not fascists. Nevertheless, it's worth preserving the institutions of a free state, simply because fighting for the inherent dignity of all men and women is, at its core, a fight against all totalitarian ideologies.
Also, it's worth remembering that Nazism and Communism were infinitely more destructive than Islamism ever will be because they controlled states. Islamism has yet to conquer a state. The "Islamic" nations are simple tyrannies, and again, Hussein's totalitarian state was not Islamic. The believers in the ideology seem to be rolling towards such a goal, and all predict forthcoming global Islamic rule, but in fact, they're simply rolling onwards, and will never reach the end of history, or the rapture, or any other happy ending.
Lastly, it's worth remembering that Arendt saw humor, joy, spontaneity, and human freedom as the direct antidote to totalitarianism, and that we should fight against any and all groups (foreign or domestic) that seek to limit these things. The answer to totalitarianism is not authoritarianism- it's liberalism.