Well in regards to refugees, Europe is dealing with the issue of people arriving and then applying for refugee status(and many aren't even seeking refugee status) where as in the US people are not brought here until after being granted refugee status . Thus far over 75% of the people who have been granted refugee status by the UN are women and children, on top of that the US prioritizes taking those who are considered more vulnerable, such as children and the elderly. So far more than half of the refugees brought to the US have been children, and another 20% have been the elderly. Only 2% have been single military aged males
In regards to terrorism in Europe, most terrorist attacks are the result of homegrown nationalist organizations, there have been no such examples of there being an attack as the result of taking in refugees, in the case of the Paris attack and the Belgium attack, all the culprits were born in Belgium.
In the US there have been 190,000 homicides since the war on terror began, and only 37 have been related to Islamic terrorism, 0 of which have been the result of taking in refugees
Rationalize it however you want, your "awareness" is a fear of Islamic terrorism
FearNOUN
1. An unpleasant emotion caused by the belief that someone or something is dangerous, likely to cause pain, or a threat:http://www.oxforddictionaries.com/us/definition/american_english/fear If it were merely awareness then your concerns would not exceed the actual level of danger that Islamic terrorism presents... "Awareness" is the knowledge or perception of a situation or fact.. your perception of Islamic terrorism exceeds the actual level of danger that exists to an irrational level. It even seems to go so far beyond the actual level of dangers into being fearful of Muslim people as a whole
Islamic terrorism would be very difficult in Europe without disaffected homegrown sympathizers. The significant presence of large, culturally distinct ethnic groups is a problem for European nation-states.
It's incredibly hard to integrate millions of immigrants when your concept of your nation is tied up in being ethnically similar. This goes all the way back to nationalism in Europe during the 19th century and the concept of self-determination.