What is the difference between Inverse Gas Chromatography (iGC) and Analytical Gas Chromatography?

The main difference between inverse GC and analytical GC is that we invert the roles of the stationary and mobile phase. So in inverse GC, we have a column, it could be a film, a fiber, a granule and we have carrier gas, nitrogen or helium and then we inject the probe molecule with known properties and measure the retention time of that probe molecule as it travel across the surface of the materials of interest.