Sanders and O'Malley said that they believe the national minimum wage should be set at $15.
Sanders has taken steps to put that policy into motion as he introduced a bill in July that would call for the minimum wage to be increased to $15 nationally by 2020.
All of the candidates have said that they will raise taxes on the wealthy. Clinton and O'Malley have not specified how much they will tax the wealthy. At one point during the campaign, Sanders suggested that he may consider raising the top tax rate to 90 percent but he has since said that he would not be as extreme and has not come up with an exact number.
Without providing a specific number, Sanders and O’Malley have said that taxes on the middle class may have to be raised a little. They both have expressed support of a payroll tax increase, which could help fund paid family and medical leave for workers. Clinton supports paid leave, but says she will fund it without raising middle class taxes and has suggested that she will pay for it using the increased tax revenues.
All three Democratic candidates are opposed to privatizing Social Security or raising the qualification age and they all want to help increase the monthly payouts to certain beneficiaries, but the ways in which those increases would come and who they would go to differ by candidate.
Sanders and O’Malley have said that they will get the money to expand social security by lifting the cap on taxable income for people earning more than $250,000, and while Clinton opposed that idea in the 2008 campaign, she said this week that she is currently considering the move.
Clinton has said that increases from her potential plan would benefit the poorest Social Security recipients while Sanders said he hopes to use the funds in order to add $65 per month for average beneficiaries. O'Malley has said that he'd increase Social Security benefits for minimum wage and lower-income workers.
Wall Street Reform
The area with the most variety in the Democrats’ proposed changes is the way in which they have said they intend to reform Wall Street, even though they all agree that it needs to be fixed.
Sanders has said Clinton can’t effectively take on Wall Street because she takes money from them, but the former secretary of state has responded by saying that anyone who knows her knows she is not that easily influenced.
The fact that the two leading Democrats differ on their approaches to Wall Street is something of a pattern at this point, as then-Sen. Clinton voted for the financial bailout in 2008 and Sanders voted against it.
All three of the Democrats want to strengthen the Dodd-Frank laws governing financial markets, instill a financial transaction tax on high-speed trading, and slow the so-called revolving door between government and Wall Street.
All three candidates have released plans for infrastructure improvements, though they show a massive range in cost.
Sanders proposed investing $1 trillion over five years -- a move that he thinks will put at least 13 million Americans to work -- in an effort to rebuild roads, bridges, railways, airports and dams.
Clinton's plan costs $275 million over that same time period. She also wants to create a $25 billion national infrastructure bank.
ABC News' MaryAlice Parks contributed to this report.