How is diffusion both small-scale (global) and large-scale (local)?

Diffusion could be small-scale because a new idea in a culture could have developed and that idea is only spread through that culture only. An example of this would be Cajun culture in Louisiana. Diffusion could be large-scale because of the globalization of new ideas through the globe. An example of this would be the diffusion of Chinese culture in the United States because immigrants migrate to the United States and bring their culture with them. This is why we have Chinese food and Chinese architecture in the United States.

Their worse are not meaningful;