Jonas's community is an attempt at a utopia – a perfect society with no pain, suffering, or violence. But, as we see from reading, there are clearly some problems here. There's no freedom, choice, or individuality, and the novel argues that this price is just too high to pay for mere contentment. So, because The Giver portrays a failed utopia, it is anti-utopian or a dystopia – a world in which everything has gone wrong.
Moving on to the next category, take a look at the world in which The Giver takes place. In this futuristic society, humans are genetically engineered to stop seeing color. The climate and topography are scientifically controlled. We don't know the details of these techniques, but it's plot elements like these that warrant the "science fiction" label.