The Affordable Care Act and the Paul Ryan budget illustrate the difference between Democratic and Republican approaches to Medicare spending. Democrats want to keep offering people good care and save money by driving harder bargains with the corporations who sell it. Republicans want to keep offering corporations sweet deals and save money by giving people less care.
This is the basic way that the parties' approaches to spending differ. It's not so much a matter of how much they'll spend, but which class of recipients will get the money.