It has been said that "An eye for an eye, a tooth for a tooth" is a terrible guide for personal action, but when deciding judgment, it's a very good rule of thumb. This makes sense to me: on a personal level, attempting to avenge every slight made against you is the stuff of feuds, and is especially tragic when the original party meant no offense, and would have gladly made things right if only you had brought the matter to their attention. When judging between two parties, however, once it's made clear that an offense has been made, this is clearly a fair way to make amends.
Now, consider this saying by Karl Marx: "From each according to his ability, to each according to his needs." This saying has a similar private/public dichotomy.
As a guide for private action, this is fantastic: I figure out what my interests and abilities are, and then match them to the needs of those around me, who will then pay me to do those things. While this won't necessarily make me rich, it will certainly enable me to live comfortably...and with my material wealth, I can now seek out those who are in dire need, and figure out the best way to help them. Sometimes it will be by giving them food and instructions on how to budget their paychecks; other times, it may be to help restore a house burned down by fire; yet other times, it may be to just tell them to do something useful with their lives.
As a guide for public policy, however, it is a disaster. A bureaucrat at some level or another must decide what an individual's "abilities" are--and then confiscate them. Thus, people are forced into careers they have no interest in, and if they have any success, their wealth must be confiscated, and given to those who are "poor", but are likely only poor because they aren't working hard at something they enjoy doing. Of course, the bureaucrat only encourages people to become poor by providing for them, and by beating down anyone who shows any sign of succeeding.
Unless, of course, we're discussing the success of the bureaucrat. He's just doing the People's work, mind you, so he deserves his wealth.
The difference between the two is this: in the first instance, it is the individual taking initiative, and deciding the best ways to make the world a better place.
In the second case, it is the bureaucrat making the decisions, without regards for individuals. The result is massive alcoholism, suicide, and camps filled with people who refuse to go along with the Utopian ideal.
Isn't it amazing what a difference Individualism makes?