Jonas lives in a community where sameness is the norm. The community is governed by strict rules for everything from where to put leftover food after a meal to what job one can have. People wear similar clothes, live in houses that all look the same, and work in careers that are chosen for them by a committee. Knowledge and information are also closely regulated.
When it comes to material items, there is equality for the citizens of the community. No one goes hungry. No one is homeless. There is no war and no real pain because the people are sheltered from the harsh realities of life. The Giver is the one who holds the painful memories and the knowledge they bring. These are some of the reasons that sameness can be seen as an advantage.
People in the community do not have the power of choice. They cannot choose their house, their career, or their spouse. Everything is arranged for them. Rules regulate large and small aspects of life. Each day is a repetition of the one before. If people do not conform, they are reprimanded. Jonas remembers how this happened to his friend, Asher, many years before when they were three. Young Asher had said the word "smack" when he meant "snack." Asher had wanted to eat a snack. Jonas recalls what happened:
The other Trees, including Jonas, had laughed nervously. "Snack!" they corrected. "You meant snack, Asher!" But the mistake had been made. And precision of language was one of the most important tasks of small children. Asher had asked for a smack. The discipline wand, in the hand of the Childcare worker, whistled as it came down across Asher's hands. Asher whimpered, cringed, and corrected himself instantly. "Snack," he whispered (The Giver, Chapter 7).
If someone continues to have trouble conforming, there can be even more dire consequences. People who break too many serious rules might even be released, which means that they are euthanized. These are some of the reasons that sameness can be seen as a disadvantage.
Advantages: Conformity and "sameness" help to stabilize a community. If everybody acts in accordance with the rules and laws, then a sense of security is given to the community. Additionally, negative emotions toward fellow community members is more or less non-existent. Things like racism and bigotry cease to exist, because everybody is the same. Along those lines, jealousy is removed in large quantities too, because nobody has or does anything that the other members of the community also don't already have or do. Conformity also makes enforcing the laws and rules much easier. Anybody that does not conform really sticks out as odd.
Disadvantages: Total conformity doesn't allow any single individual to express himself/herself. There's no "pushing the limit." I don't mean breaking rules. I mean there's no incentive to try and push yourself. Almost all independent thought ceases to exist, and independent thought has made some great men in history -- Newton, Galileo, Einstein, Tesla, Edison, etc. If they were forced to conform, their scientific contributions would never have materialized. And that's just science. What about art and literature?
Biologically, conformity is not healthy. A diverse genetic gene pool is absolutely essential for the survival of a given species. If there is genetic conformity, then there is less genetic diversity. That has never worked out well for species, because it leads to inbreeding and genetic mutations.