The only difference is Europeans can unify under the banner of being French or Italian despite race as long as you're not a recent immigrant bringing a different culture opposite from the dominate one.
In order to assimilate there has to be something to assimilate too.
This explains white american culture to some degree.
In his 1989 book "Albion's Seed: Four British Folkways in America" (ISBN 0-19-506905-6), David Hackett Fischer explores the details of the folkways of four different groups of settlers from the British Isles that came to the American colonies during the 17th and 18th centuries from distinct regions of Britain and Ireland. His thesis is that the culture of each group persisted (albeit in modified form), providing the basis for the modern United States.
According to Fischer, the foundation of America's four regional cultures was formed from four mass migrations from four different regions of the British Isles by four distinct ethno-cultural groups. New England's formative period occurred between 1629 and 1640 when Puritans, mostly from East Anglia in England, settled there, thus forming the basis for the New England regional culture. The next mass migration was of southern English cavaliers and their Irish and Scottish servants to the Chesapeake Bay region between 1640 and 1675. This spawned the creation of the American Southern culture.
Then, between 1675 and 1725, thousands of Irish, Cornish, English and Welsh Quakers plus many Germans sympathetic to Quaker ideas, led by William Penn, settled the Delaware Valley. This resulted in the formation of the General American culture, although, according to Fischer, this is really a "regional culture," even if it does today encompass most of the U.S. from the mid-Atlantic states to the Pacific Coast. Finally, a huge number of settlers from the borderlands between England and Scotland, and from northern Ireland, migrated to Appalachia between 1717 and 1775. This resulted in the formation of the Upland South regional culture, which has since expanded to the west to West Texas and parts of the U.S. Southwest.
In his book, Fischer brings up several interesting points. He states that the U.S. is not a country with one "general" culture and several "regional" culture, as is commonly thought. Rather, there are only four regional cultures as described above, and understanding this helps one to more clearly understand American history as well as contemporary American life. Fischer also asserts that it is not only important to understand where different groups came from, but when. All population groups have, at different times, their own unique set of beliefs, fears, hopes and prejudices. When different groups came to America and brought certain beliefs and values with them, these ideas became, according to Fischer, more or less frozen in time, even if they eventually changed in their original place of origin.