If you refer for example to electrons in metals, clearly the thermal velocity of electrons which contribute to conductivity, which are those at the Fermi energy, is much much much larger than the drift velocity known from the Drude model. The drift velocity is the remaining net velocity, e.g. due to the presence of an applied electric field, after averaging out the random thermal motion. What changes in nanostructures is the possibility for ballistic transport. In this case the structure dimensions are so small that the electrons are not scattered via electron phonon scattering before they run into the geometric constraint. In this case transport can no longer be considered in the Drude model via a relaxation time due to scattering.