More individual freedom and prosperity under capitalism.

The main difference is that under communism, most property and economic resources are owned and controlled by the state (rather than individual citizens); under socialism, all citizens share equally in economic resources as allocated by a democratically-elected government.

Bernie advocates for government control of some parts of the economy; most notably health care and energy.

He's a Socialist. I'm sure he has a copy of the Communist Manifesto on his bookshelf.