The following I have taken from http://www.diffen.com/difference/Communism_vs_Socialism. While I do not entirely agree with everything the comparison says, it should give us some idea about differences. The way I see it, socialism is simply another form of communism wrapped up in progressive’s clothing. Some of the differences are somewhat artificial, since “freedom” and “liberty” become relative terms in socialism. They are still given and taken away by the state, just as in communism. Anyway, here’s what the site says:

In a way, communism is an extreme form of socialism. Many countries have dominant socialist political parties but very few are truly communist. In fact, most countries – including staunch capitalist bastions like the U.S. and U.K. – have government programs that borrow from socialist principles. “Socialism” is sometimes used interchangeably with “communism” but the two philosophies have some stark differences. Most notably, while communism is a political system, socialism is primarily an economic system that can exist in various forms under a wide range of political systems.

Comparison chart

Improve this chart Communism Socialism
Philosophy: From each according to his ability, to each according to his needs. Free-access to the articles of consumption is made possible by advances in technology that allow for super-abundance From each according to his ability, to each according to his contribution. Emphasis on profit being distributed among the society or workforce in addition to receiving a wage.
Definition: A theory or system of social organization based on the holding of all property in common, with actual ownership ascribed to the community or state A theory or system of social organization based on the holding of most property in common, with actual ownership ascribed to the workers
Political System: One-party system. A dictator or elite leader has absolute control over citizens. Multiple parties, but the ruling party usually goes by the name “Socialist”.
Social Structure: All class distinctions are eliminated Class distinctions are diminished
Ideas: Human societies have always been divided into warring classes. The Industrial Revolution has enriched the wealthy and impoverished the poor. The workers must overthrow the bourgeois. All people should be given an equal opportunity to succeed. Workers should have most say in their factory’s management. The free market suffers from problems like tragedy of the commons. Government regulation is necessary.
Economic System: Wealth redistributed so that everyone in society is given equal shares of the benefits derived from labor. All means of production are controlled by the state Wealth redistributed so that everyone in society is given somewhat equal shares of the benefits derived from labor, but people can earn more if they work harder. Means of production are controlled by the workers themselves.
Key elements: An enhanced form of the principle of “Production for use”. Economic activity and production especially are adjusted to meet human needs and economic demands. “Production for use”: useful goods and services are produced specifically for their usefulness.
Free Choice: All choices, including education, religion, employment and marriage, controlled by the state All choices, including education, religion, employment and marriage, are up to the individual. All health care and education is provided free to everybody
Ownership structure: The means of production are commonly-owned, meaning no entity or individual owns productive property. Importance is ascribed to “usership” over “ownership”. The means of production are socially-owned with the surplus value produced accruing to either all of society (in Public-ownership models) or to all the employee-members of the enterprise (in Cooperative-ownership models).
Private Property: Abolished two kinds of property, private property, such as land, houses, clothing, etc. owned by the individual. Public property, factories, and means of production owned by the state but with worker control
Economic Coordination: Free-access distribution. Planned-Socialism relies principally on planning to determine investment and production decisions. Planning may be centralized or decentralized. Market-socialism relies on markets for allocating capital to different socially-owned enterprises.
Religion: Abolished freedom of religion
Political Movements: Leninism, Trotskyism, Marxism-Leninism, Maoism, Left-Communism Democratic Socialism, Communism, Libertarian Socialism, Anarchism, Syndicalism
Discrimination: In theory, all members of the state are considered equal The people are considered equal, laws are made when necessary to protect people from discrimination
Key Proponents: Karl Marx, Fredrich Engels, Vladimir Lenin, Leon Trotsky Robert Owen, Pierre Leroux, Karl Marx, Fredrick Engels, John Stuart Mill, Albert Einstein, George Bernard Shaw, Leo Tolstoy, Emma Goldman
Means of control: Proletariat engages in violent rebellion. Proletariat engages in taking charge of the factories and means of production.
Variations: Include Marxism, Leninism, Stalinism and Maoism libertarian-socialism, and anarcho-socialism, anarcho-syndicalism
Way of Change: Government in a Communist-state is the agent of change rather than any market or desire on the part of consumers. Change by government can be swift or slow, depending on change in ideology or even whim. Workers in a Socialist-state are the agent of change rather than any market or desire on the part of consumers. Change by the workers can be swift or slow, depending on change in ideology or even whim.