Contagious would be migratory labour. Such as Mexican workers going to the US to work and bringing with them new agricultural techniques.
Hierarchical would be manufacturing firms relocating or...
Expansion diffusion means that the diffusion expands in the area you are in. Relocation diffusion is when you have spread something where you are, and then move(relocate) somewhere else, spreading it...
Diffusion: Diffusion describes the spread of particles through random motion from regions of higher concentration to regions of lower concentration. The time dependence of the statistical...