Thermal space plasmas have generally been modeled either by direct solution of the collisionless Boltzmann equation or by solving a set of transport equations obtained by multiplying the Boltzmann equation by suitable velocity moments and integrating over velocity space. The former approach gives the spatial-thermal variation of the distribution function itself, whereas the latter approach provides only partial information regarding the distribution function through the spatial-temporal variation of a finite number of velocity moments. However, the transport approach can easily incorporate the effects of collisions and chemical reactions into the description, whereas a direct solution of the Boltzmann equation (the kinetic approach), in any but a collisionless regime, has proven to be difficult. A vast body of work has been done in space plasma physics in which either a transport (e.g., hydrodynamic, hydromagnetic, generalized transport) or a kinetic (e.g., fully kinetic, semikinetic) approach has been employed. In order to properly understand the significance of this work, it is critical that a better understanding be gained of the relative merits of the transport and kinetic approaches. As a first step in this direction, a comparison has been made, in as consistent a manner as possible, of a transport (bi-Maxwellian based 16-moment equations) and a semikinetic description of supersonic flow in the solar wind and also of both supersonic and subsonic flows in the polar wind for ''steady state'' conditions. The study shows: (1) remarkable agreement between the two models for supersonic collisionless flows, even for the higher-order moments; (2) the inadequacy of the semikinetic approach for modeling subsonic flows; and (3) the superiority of the 16-moment transport over the semikinetic approach for modeling the solar wind. Our study provides further evidence that the bi-Maxwellian based transport equations are a useful tool for studying ''thermal'' space plasmas that develop non-Maxwellian features. ¿ American Geophysical Union 1992