The conflict of the story is when Jonas learns that his community is killing babies.
The internal and external conflict are dependent on the dystopian setting.
Jonas’s community is supposedly perfect. They have put a lot of effort into ensuring that. In order to maintain this perfection, the community employs what is known as Sameness. Sameness means that everything about the community is tightly controlled.
Anything that might upset someone or make things difficult to do is prevented. This includes population control, and even control of the environment.
"Climate Control. Snow made growing food difficult, limited the agricultural periods. And unpredictable weather made transportation almost impossible at times. It wasn't a practical thing, so it became obsolete when we went to Sameness.
"And hills, too," he added. "They made conveyance of goods unwieldy. Trucks; buses. Slowed them down. So--" (Ch. 11)
The idea is to make sure no one is ever uncomfortable. This is why the community has rules of language that are so strict. There are rules for everything in the community. Breaking a rule three times, or breaking one serious rule, results in release.
Jonas does not know what release really means until the incident with the newborn twin. Twins are not allowed in the community because they might make someone uncomfortable. Identical twins are not allowed.
The Giver's face took on a solemn look. "I wish they wouldn't do that," he said quietly, almost to himself.
"Well, they can't have two identical people around! Think how confusing it would be!" Jonas chuckled. (Ch. 19)
It is at this point that the story reaches its climax, or turning point. Jonas has been slowly learning just how wrong the community is to do away with concepts like love and family. Now he understands that a travesty occurs regularly in the community. Innocent babies are killed to keep people from feeling uncomfortable.
Jonas’s internal conflict is the struggle that he faces to reconcile the understanding of what his community does with the perfect world he thought he lived in. The external conflict is Jonas versus his community, when he decides he has to do something about the horrors of his community.