What makes a book dystopian?  A perfect futuristic world with a controlling government and where everyone is happy. The government is stable and works well and nobody questions anybody's motives.  That is, until some young person comes along and starts to rebel against everything.  They become curious or realize that they are better than this and break free.  But before that happens, isn't everything basically a utopia?  Some books have special ways to control their residents by drugging them or taking away some important ability from the people. 
In The Giver, by Lois Lowery, the people each have a special job to help out the community.  Everyone is polite and kind to each other, and students respect their elders.  People are put together as man and wife because they are compatible with each other, not because they love each other.  The children are given to the parents instead of them giving birth to their own child.  They are expected to raise and love their child and to not question why things are this way. Another thing that I find the most interesting about this world is the fact that they see no colour.  There is no colour except for blacks, whites, and greys. 

In Matched by Allie Condie, people take pills every morning.  The pills are different colours, and each one may do something different. One may make you forget, where as others may surpress your emotions and feelings. The governments in dystopian novels think that they can control the people by pills or fear or prevention of reading. In Matched, people weren't allowed to read, and that's one of the big things in the series, that the main characer learns how to read.

So, with these two examples, I'd like to point out that the governments always decide that people can't make their own choices, so someone must make them for them in order for people to survive.

My list in order of most controlling, to least controlling would be:
The Giver by Lois Lowery
Matched by Allie Condie
Uglies by Scott Westerfeld
Divergent by Veronica Roth
Legend by Marie Lu
The Hunger Games by Suzanne Collins

My reasons for this list is because in The Giver, the people had everything taken away from them, including their right to have their own children or chose their own spouse.  Children and spouses were assigned as were jobs and houses.

In Matched, the people are surpressed by pills, and as teens, their future spouse is chosen for them and they are given a profile of them, along with as much time as they want to get to know them.  Yes, that sounds a little more freeing, but your spouse is still chosen for you and you still have to take the pills.

In Uglies, the people get to undergo a transformation to make them "beautiful" but at a price.  I think that it's a little sickening the way they alter the people, but it's still a very good series.

In Divergent, I would have put it closer to the "less controlled" except for your future is chosen for you.  Your "faction" is chosen due to an aptitude test, and if you don't do well in your perspective faction, you can't go back to your old faction.  "Faction before blood." is their motto.

In Legend, though I've only read the first book, it didn't seem too controlling.  I'll tell you more on that when I've finished the series.

And now you may be wondering why I put The Hunger Games as last.  Well, because even though you are split into districts and every year there is a reaping for kids from 12 through 19, it's not nearly as controlling as the other books because it's much easier to slip under the radar and to stay hidden and to do whatever.  Yes, your actions are monitored, but as Katniss proved, there are loopholes and you can slip away. 

So basically yeah, these are some points on what truly makes books dystopian.  A controlling government, a rebellious protagonist, and some world where everything seems perfectly at peace.