• They're less likely to have a job. Just two-thirds of high school-only grads ages 25 through 64 were employed in 2015, down from 73 percent in 2007. For college graduates, 83 percent were employed, down from 84 percent.

• They are less likely to be married. In 2008, marriage rates for college-educated 30-year-olds surpassed those of high-school-only grads for the first time.

• High school-only grads are less likely to own homes. Sixty-four percent are current homeowners, compared with 77 percent of bachelor's degree holders.

• College grads are more likely to contribute to a 401(k)-style retirement plan. College grads contributed 26 percent more even when members of both groups had similar incomes and access to such plans, research has found.