A comparative study has been performed for properties (temperature, density, and electron Coulomb coupling constant) of plasma induced by high-intensity ( ∼ GW/cm2) nanosecond laser-metal interactions in air, water, and vacuum. The study is for early-stage (t≲30 ns) plasma evolution, where the above plasma properties are very difficult to measure experimentally and hence a comparative property study has been rarely reported in literature. In this paper a physics-based predictive model is used as the investigation tool. The model was verified based on experimental measurements for the early-stage plasma pressure and front propagation and the late-stage (t≳30 ns) plasma temperature and electron number density, which are relatively easy to measure. Therefore, the experimentally verified model can provide reasonably accurate information on the difficult-to-measure plasma temperature and density in the early-stage at least in the semiquantitative sense, and the information will be very useful for the fundamental laser plasma study and relevant laser applications. It has been found that plasma with very different temperatures and densities can be created in different media.