Cultural Diffusion: The spread of cultural traits from one society or region to another through contact between individuals or groups. For example, the popularity of sushi spreading from Japan to other parts of the world.
Acculturation: The process in which an individual adopts certain aspects of another culture while still retaining their original cultural identity. An analogy for this would be someone adding new toppings on their pizza without changing its basic crust and flavor.
Cultural Assimilation: When individuals fully adopt the practices and values of a different culture and give up their own cultural traditions. This can be compared to blending colors together where the original colors are no longer distinguishable.