Conduction: transfer of heat from one molecule to its neighbor by means
of thermal collisions.

Convection: transfer of heat from one location to another as kinetic
energy of a group of molecules of a fluid. (usually driven by the
effects of gravity on differential densities as in the Archimedes
effect)

Diffustion: *also* transfer of heat from one location to another as
kinetic energy of a group of molecules of a fluid. Distinguished from
convection in that the random thermal motion of the molecules provides
the transport.

Radiation: transfer of heat from location to another by means of
electromagnetic radiation. No medium is required as radiation can
traverse a total vacuum. [The sun sure is hot today, isn't it?] If a
medium is present it must be at least partially transparent to the
particular wavelengths of radiation involved.

Heat can also be transported by converting it to another form
(typically electrical or chemical energy) top be placed within a
material, which itself is transported (or in the case of electricity is
electrically conducted) to another location where the heat can be
released.

HTH

Tom Davidson
Richmond, VA