The difference is that all the countries this little piece of hate fiction is banned in are democracies. So if people want that particular law changed all they have to do is create a party that has the abolition of such limitations on free speech as one of its (key) policies and convince people to vote for them, which would remove the restriction.
Whether a policy can be altered is irrelevant when determining whether or not it's a good policy. "If you don't like it, get it changed" is really in my ears "***** you, I'm not discussing this with you". This "My way or the highway" philosophy is precisely what you get when the State starts telling people what sentiments they are allowed to express.
Until such the laws are actually part of what the people want, not random government enforced restrictions.
Righty, and people who do not want them can express this opinion freely without fearing for a blow to their reputation or a stigma as a "Nazi supporter", I assume

.
The fact that such parties do not get a majority might not be something you like, but its hardly undemocratic.
What would be "undemocratic" in your eyes? A bill banning minarets? A bill exiling all foreigners of Asian descent? A bill requiring all atheists to wear identifiable scarlet "A"s on their clothes so people could identify and shun us? Sorry, but the majority may decide what gets done and what doesn't. It does not, however, simply by being the majority, decide what is and isn't moral.
Suppose I published a book depicting your recent ancestors as cannibals, but stating that the contents were only based on my opinion. Would that be acceptable?
Absolutely. Of course, if the book was proven to be false you would be subject to applicable libel laws, but publishing the statements would still be perfectly legal. Heck, you could publish a book branding me as a serial rapist of children and ruin my life, and I wouldn't argue that the book should be banned.
Oh, and it doesn't matter if it's "only based on opinion". Free speech is free speech. It doesn't matter if it's "just my opinion", a "fact", or "just asking questions" that the PRC's government stinks, I'm allowed to say it. It doesn't matter if it's "just my opinion" if I say I'm going to kill you on Thursday, it's still illegal.
Also, what are these questions that you're not allowed to ask?
Oh, so you can be a Holocaust-denier in Germany, as long as you phrase them as questions

?
Some questions on independence
I'm just wondering -- and pardon me if you take me as, like, a rebel or progressive or something here, because we're totally not thinking of forming our own nation or anything, that'd be politically incorrect -- but I just wanted to know if it's true that all men are created equal, endowed by their creator with certain unalienable rights, such as Life, liberty and the pursuit of happiness? Just asking questions is all. Now I just also wondered if His Majesty kenw if Governments could be instituted among Men, deriving their just powers from the consent of the governed? Just asking, no sentiments expressed here, nossire. Now, while we're on a roll, could you tell me if...
...goes on for a while...
Now, would you mind if we, like, threw this ship load of tea on the sea and declared independence really quick?
King George V (puzzled, scratching head): Do we have a revolution on our hands?
Aidee: Nah, he's Just Asking Questions.
Oh, and have you stopped beating your sis' yet?