The history of Quark Gluon Plasma (QGP) physics have shown that while lattice QCD can predict some observables the physical picture, e.g., the degrees of freedom, is hard to extract. In this talk I consider some simple QGP/hadrons gas pictures in different limits, gluons only (pure Gauge) and massless light quarks, to see if one can get a more intuitive understanding for why the order of the phase transition changes from Xover (our world) to 1st order. The hope is that in this way one can get some insight into what the QGP is.