Sometimes, the term convection seems to include advection and
diffusion, sometimes not. After all, equations exhibit two
different terms for advection and diffusion, and we don't call
the sum of them a convective term. When we talk about a
convective term, it is indeed the advective term! transport of
pollutants in a river by bulk water flow downstream relates to
advection boiling water for pasta relates to convection Maybe, a
conserved property such as energy can be advected, but we only
use convection for transport of "ensembles of molecules". So, is
there a difference? Could we figure it out with examples?