The stories are based around a future with high level technollogy that allows a select group of huimans to live in peace. Yet there is a dark secret behind the societies that they are living in. Both happen to feature young males whose perspective of the world is naive, not to mention innocent of the way the world looks. But when someone suddenly shows up, a person very mysterious, suddenly, their lives end up being turned upside down.
Stories set in a possible future that deal with the gradually revealed Orwellian control exercized over the people by government institutions and involve advanced technology for everyday use.
Both are about a world that is ideal in some way, and both of these ideal worlds have a dark secret behind. In no.6 a chosen ignorant group of people can live in bliss, and everyone who dares to have a different opinion are eliminated, reminds me of communism a bit. In Fractale everyone lives in a so called free world and receive a brainwashing frequently, so that no one would have doubts or questions.
I think no.6 is deeper, darker and I personally liked it more. Fractale is a lot more light and childish, but enjoyable nevertheless.
Both anime present a technologically advanced, seemingly utopical world, with a lot more going on behind the curtain. The main characters are teens who accidentally find out about these secrets and oppose the authorities.
Both are noitaminA shows with a "social sci-fi" feel, with some similar themes. The difference is that No. 6 is a more blatant dystopia from the beginning while Fractale makes a point of showing both the good and the bad of the society it depicts. Also No. 6 has more yaoi.
The plot revolves around some kind of ideal city and the main character founds out about it's secrets.
The story focus on characters fighting against a utopian city that once they thought it was a safe and normal place. Both main characters slowly discover the secrets of the city they live in and stop being ignorant after finding someone who teach more about the world to them.
If you've seen Fractale you will agree that they give off a really similar feeling, and are surrounded by technology, and don't need to worry about safety because they are protected by the system. Even the art style is somewhat similar. Later on when the story progresses, it reveals the flaws in the cities "perfect" system. These series even have the same number of episodes.
Both series are rife with inconsistancies and plotholes which are never fully explained. they start out great presenting this idea of a utopian world, but soon shows that all is not as it seems. the worlds and styles are very similar, but could have benefited from a longer run time and more character development
Both Series are based on some really high tech that allows most people live the way they wanted, both series has amazing plot and character design if you like the one you'll like the other
Both are set in dystopian world's that seem perfect to the happy inhabitants but harsh truth is revealed once an outsider to the world shows the MCs the truth.