The Bipartisan Policy Center's Loren Adler posts this graph looking at how much various deficit reduction plans would spend on health care. One of these things, you can pretty easily see, is not like the other:
Most of that difference is not related to Medicare, even though Medicare cuts are the ones we've been talking about a lot lately. Instead, Adler says, "the difference stems almost entirely from less spending on Medicaid, CHIP, and [Affordable Care Act] subsidies." (CHIP refers to the Children's Health Insurance Program, jointly funded by the federal government and the states.)
Ryan's is the only plan here that would repeal the Affordable Care Act, which would eliminate a lot of spending on insurance subsidies. Combined with the GOP vice presidential nominee's big Medicaid cuts - you can read more on that from Suzy Khimm here - that pretty much explains why Ryan would be spending a lot less on health-care programs than would Obama.