evolution and adaptation is necessary for your right to existence. being rigid and stubborn as a mule leads only to stagnation and strife.
this is why I don't trust anyone wearing a headwrap.

The major difference between these two is time. Given enough time (roughly 3 to 4 generations) and of course your own contribution immigrant groups will assimilate into the local culture. You shouldn't expect immigrants to assimilate into their host's culture immediately. The muslims in Russia went through this process centuries ago.