You know how Obama got the Nobel peace prize as soon as he was president, before he actually did anything?
There would be some equivalent anti-peace prize awarded to Trump as soon as he becomes prez. :(.
To be more pragmatic, it all depends who is in Congress. Obama has struggled to do anything with a consistently hostile Congress. If Republicans are majority party, they will pressure Trump to go along with the Rep. party pet issues, so that Trump in return can get thru some things he likes (horse trading, yes?). The party wants to remove all the peace deals with Iran (& possibly Cuba, too). That will be near top of their list. Trump has pledged to build up military capacity & Republicans love that (military-industrial complex build up, money for special interest lobbyists in constituencies). The tobacco industry may get a resurgence. At this rate Trump will appoint next Supreme Court justice, and the Party will probably choose that person (someone with extremely socially conservative views).
Trump has planned corporate tax cuts: he believes in trickle down economics, and less regulation -- although I'm not sure it's possible for the fed. govt to become any more gutted in its regulatory powers than it was under GW Bush. Republican party will be fine with that, since it benefits their big donors. Plus Bush & cronies made a huge amount of money out of contracts (read Molly Ivins' Bushwacked book, if you can stomach it) so Trump will probably nurture similar types of cronies in return for cooperation of the Rep. party in Congress. True immigration limits hurt big business, but the party will go along with it if they get the other things on their shopping list. Trump and the Rep. party both want more privatisation for public services.
Trump has pledged to dismantle Obamacare, which probably means gutting Medicaid, too. Trump wants to gut trade deals which could make American manufacturing exports harder to sell, but things like arms, tobacco, services will still sell well, so palatable for many Congress-reps.
Things that could happen under Prez Clinton but won't happen under Prez Trump; Federally funded Research into gun violence, limiting access to guns or broadening access to abortion, federal money for preschool places (generally doesn't exist), more drop-in clinics for medical care, better funding structure/loans scheme for university courses, continued & expanded subsidies for renewable energy.
Tax cuts for the lower paid, or expanded social security are moot issues: Republicans may concede this to Prez. Trump if they win on their pet issues (like renewed hostility with Iran). Clinton may see those as negotiable, too.
Hillary basically wants to continue much of what Obama has done and Trump has pledged to reverse a lot of it.
Trump's border "wall" will probably turn out to be extra barbed wire.
Trump talks a populist agenda, but he is very much a corporate fat cat.