Socialists, Progressives, Communists, and Democrats; What are the differences?

Bernie Sanders is a socialist.  Hillary swears she's no socialist, she's a progressive democrat. Barack Obama swears he's no socialist either.  No one openly admits to being a communist.  What are the differences between these philosophies?

I maintain the above question is the wrong question.  The correct question is, "what unites these philosophies?"  The differences all relate to tactics and emphasis, not philosophy.  The underlying philosophy is the same in all cases.

Socialists, progressives, communists, and modern democrats in the U.S. are all Marxists.  They all believe as their foundational tenet in government coerced egalitarianism (equality of stuff).  The Marxist slogan, "From each according to his ability, to each according to his need.", applies in all cases.  This is not organic egalitarianism.  It is imposed by the government through force.

Democrats and progressives want to impose this Marxist utopia gradually and nominally through the political process, but they cannot reveal their intentions.  Socialists want exactly the same thing, only they are willing to reveal their intentions.  Communists are different only in that not only are they willing to reveal their intentions, they hope to achieve their utopia through revolution.

But in all cases utopia is the goal and it is the same vision despite some differences in detail.  Never is there a limiting principle.  In other words, how would a progressive know when the work is done? How would they know when the utopian dream has been achieved?  They cannot tell us.  

Progressivism and progressive democrats in the U.S. are unique.  That's because those terms relate specifically to our constitution.  The constitution is a formidable roadblock to Marxism.  Therefore, it must be relegated to the dustbin of history.  Progressivism means progressively dismantling the constitution.  Where will this progress end? Only when the constitution is completely dead.  It must be destroyed because it alone stands in the way of the Marxist utopia.

What makes America exceptional are the ideas on which it was founded.   Primary among them are the ideas that we are all equal in our rights, our relationship to the law, and the governments job is to protect the rights of the individual.  Marxism turns those ideas upside-down and puts the government over the individual in order to impose equality of outcomes.

So this is what it means when you hear a politician claim, "I'm no socialist/communist/Marxist, etc. I'm a progressive democrat!"  There is no difference.