The difference to me is context. I admit that I don't have a great recollection of the details of Obama's refugee ban, but from what I remember I have no reason

The difference to me is context. I admit that I don't have a great recollection of the details of Obama's refugee ban, but from what I remember I have no reason to believe that he was motivated by something other than national security risk (whether or not the risk was significant enough to justify the ban is something I don't claim to know). But the context of Trump's ban is very different. He promised a Muslim ban during his campaign, and according to Rudy Giuliani (tonight on Fox News), Trump asked him for advice on implementing the Muslim ban but in a technically legal way. I see no reasonable interpretation of this as anything other than Trump's team's best effort to discriminate against Muslims while being technically legal.