smoothing round shapes means: basicly there are two kinds of shading methods in 3D: smoothed and flatshaded. You may try it in a little blitz program, create a sphere and display it. Then add the EntityFX command for flatshaded (see docs) and compare the result.
Gile[s] is using some kind of smoothing groups to lightmap convertion. Other Lightmappers simply save things flatshaded.
Example:
flatshaded columns with Maplet:

smoothed columns with gile[s]:

Although you can see a seam on the near columns, the distant columns are smootly shaded and appear round. The seams make clear gile[s] needs some manual adjustment of the smnoothing to make it look best.
Gile[s] is using some kind of smoothing groups to lightmap convertion. Other Lightmappers simply save things flatshaded.
Example:
flatshaded columns with Maplet:

smoothed columns with gile[s]:

Although you can see a seam on the near columns, the distant columns are smootly shaded and appear round. The seams make clear gile[s] needs some manual adjustment of the smnoothing to make it look best.