Michael P. answered • 08/03/19
PhD in Chemistry - Application of Physics to Chemical Systems
Conduction is the transfer of heat between two bodies at different temperatures in physical contact. Consider a copper block at a lower temperature placed in contact with an aluminum block at a higher temperature: Heat is "conducted" (flows) from the copper block to the aluminum block. Conduction between condensed phases (solids and liquids) is easy to visualize because the mechanism behind conduction is the vibrations of of atoms and molecules at the interface between the phases.
Diffusion is the transfer of matter over some distance as the result of atomic or molecular motion. Diffusion of one gas into another is easy to visualize, but diffusion can occur across the interface of solids, liquids, and gases.
