This is a topic where intention must be determined up front. It is not about dictionary definitions. These terms have different meanings to different people and each’s motives have to be taken into account.
That said, pluralism includes in it’s definition, “A social system that permits smaller groups within a society to maintain their individual cultural identities.” OK…sounds good, but doesn’t necessarily sound like assimilation, per se. Actually it has a ‘balkanization’ feel. ‘Enclaves’ don’t seem to turn out well for anyone. Ask a Parisian about ‘banlieues’. I guess it would depend on how strong the cultural identity is of this small group, or how ‘opposed’ the cultural identity is from the destination culture, i.e. comparing New York’s Little Italy with Paris’ Banlieues.
Does ‘incompatibility’ have a place in this discussion? I’m told in the interview process for US citizenship, candidates are to this day still asked about affiliation with communism. Not a very ‘pluralistic’ question to ask. Of course this brings up the other elephant in the room — Islam and Islamism. How much of Islam is religion, how much is (or becomes) a political system? What is the tipping point from one to the other?
To be clear, no one on either side arguing for or against diversity of food, music, poetry, etc. Let’s ‘keep it real’ here. We’re talking about borders and immigration. Rubber, meet road.
The most virulent, anti-Western, blood thirsty of jihadists is capable of cooking a mean kabob, but do we really care? So then the question becomes one of filtering the good from the bad. How to do in a non-‘hamfisted’ way, ala Trump?
The concept (religion?) of Diversity, to me, links to that typically pleasant sounding but suicidal concept of ‘the free movement of peoples’, i.e. Open Borders. History is replete with examples of failed societies unable to manage their ‘membership’.
The Neomarxist Postmoderns, hellbent in their feeble minds on revolution and destruction, are ones to beware in this discussion, along with their assorted enablers and useful idiots, that is.