Syria and most of Africa are not "known terror states", or at least they weren't before the nightmares of civil war that enveloped them and made the people flee.

But I dare to guess that you meant to say "Muslim" without saying Muslim, but even that doesn't hold as many refugees from Syria and Africa are Christians or other religions. Kurds (often Christian), jezidis, zoroastrians, ...

The only other clear differences are the proximity and skin colour of the people.

That said, Europe has always supported refugees, e.g. Vietnamese, Turkish, etc live across Western Europe. Even the Syrian civil war initially saw a warm welcome with wide open arms - it is the sheer number of people fleeing, and indeed that often mainly younger men arrived (with women less likely to flee and more like to get stuck/"married"/trafficked/killed on the way) which turned significant parts of the population to cold hearts.