Socialism

Before Marx, the term communism was used by many utopian socialists to describe an idealist, egalitarian society.

Its modern usage is almost always traced back to Karl Marx's usage of the term where he introduced the concept of scientific socialism alongside Friedrich Engels. The theory of scientific socialism described communism not as an idealistic, perfect society but rather as a stage of development taking place after a long, political process of class struggle. Marx, however, used the terms socialism and communism interchangeably and he drew no distinction between the two.

Lenin was the first person to give distinct meanings to the terms socialism and communism. The socialism/communism of Marx was now known simply as communism, and Marx's "transitional phase" was to be known as socialism.

Prolwiki > Communism > Etymology

So yes, there is a distinction between the two, but I have a feeling this isn't the distinction you were referring to.

Could you be talking about Social Democracy? Because, that's not socialism, or communism. If you're interested in this distinction presented by Lenin, you might want to read Chapter 5 of The State and Revolution.