Obama had an act in place to make it difficult for people fro these countries or who had visited these countries to get a visa. Trump expanded the "getting a visa should be difficult" part to "let's ban people from these countries regardless of if they already have Green Cards or dual citizenships".

Obama's act, though again not including countries funding and harboring terrorists, only made it difficult to get a visa which sort of makes sense but is still stupid because it didn't include Saudi Arabia and Pakistan. the ACLU protested this act but it was passed through Congress anyway