One side of the Democratic Party wants the nation’s billionaires to pay a slightly higher tax rate on their income. Through an unprecedented wealth tax, the other side would target the stock holdings, real estate and other property of the nation’s billionaires to raise trillions of dollars of new revenue. One side has virtually no plans to have the government take over private industry. The other has an armada of proposals for federal interventions, spanning from government control of American health insurance to public production of prescription drugs to mandating worker control over their companies. With Democrats set to debate again this week, the presidential primary has revealed a sharp split in the party over core tenets of American capitalism, as the months-long campaign has exposed disagreements about fundamental aspects of the nation’s economic system.