Individualism regards the individual as a sovereign being (an end in oneself) with an inalienable right to life.
According to Philosopher Ayn Rand, “Individualism regards man—every man—as an independent, sovereign entity who possesses an inalienable right to his own life, a right derived from his nature as a rational being. Individualism holds that a civilized society, or any form of association, cooperation or peaceful coexistence among men, can be achieved only on the basis of the recognition of individual rights—and that a group, as such, has no rights other than the individual rights of its members.” 
The individual can gain immense values (such as knowledge and trade) by living with other men in society if that society is a proper society. A proper society is one where every individual holds as an absolute that every person is an end in themselves and that others are not one’s pawns, nor is one theirs.
Or, in the famous words of the hero of Atlas Shrugged, John Galt,
“I swear by my life and by my love of it — that I will never live for the sake of another man, nor ask another man to live for mine.” 
Such is the credo of the individualist — the independent mind — that recognizes no authority higher than its judgment of the truth.
Individualism is not opposed to living in society, so long as one is free from the initiation of force by others. Individualism is not opposed to one living in society as a trader; it is opposed to one living as a slave. Individualism holds that it is much better for a human being to live on a deserted island than to live in a society where one is nothing more than a serf ready to be sacrificed to the altar of the “public good.”
Collectivism holds that the individual is not an end in oneself, but is a tool to serve the ends of collective.
“The political expression of altruism is collectivism or statism, which holds that man’s life and work belong to the state—to society, to the group, the gang, the race, the nation—and that the state may dispose of him in any way it pleases for the sake of whatever it deems to be its own tribal, collective good.” — AYN RAND 
Collectivism holds that the individual is not an end in oneself, but is a tool to serve the ends of others (the collective). Whereas, individualism declares that every individual should live their life for their happiness, as an end to oneself; collectivism holds the group as the primary and the standard of moral value. Whether that group is a dictator’s gang, the nation, society, the race, the gods, the majority, the community, or the tribe is merely a matter of detail.
The individual’s moral purpose is as a sacrificial victim, whose value is the ability to sacrifice one’s life, liberty and happiness to the will of the group.
Statism is a political-economic system where the individual lives not by inalienable right but by permission of the state.
Where the political result of individualism is capitalism (a social system where the individual does not live by permission of others, but by inalienable right).
The political result of collectivism is some form of statism: a system where the individual lives by permission of the state.
Under statism, the government is no longer a paid political servant or policeman, but a master with the legal power to initiate force against legally disarmed citizens.
In particular form, many of these forms of statism differ superficially, but in theory, and bloodstained practice they all unite upon the same fundamental collectivist ethical principle: the individual is not an end to oneself but is a tool to serve the ends of others. Whether those “others” are a dictator’s gang, the nation, society, the race, (the) god(s), the majority, the community, the tribe, is irrelevant — the point is that the individual is not sovereign but a serf.
Only capitalism declares that every human being, may live their own life for their happiness, as an end to oneself, not by permission of others, but by right, and that government’s sole responsibility is to protect those rights and never violate them as they are inalienable. Statism declares that each individual exists to serve the state.