Each folder corresponds to one rendering approach.
brdf.dds is texture that is used to caclculate diffuse and specular terms. Let you have

float dotNV = dot(Normal,View);
float3 brdf = tex2D(BRDF,float2(dotNV,gloss));

Then color in linear space will be represented in shader as

color = surface_diffuse_color * environment_diffuse_color * brdf.z + (surface_specular_color * brdf.x + brdf.yyy) * envirinment_reflection_color



surface_specular color is not calculated in shader, it is calculated wihin 3D-Coat

surface_diffuse_color = albedo * (1 - metalness)
surface_specular = albedo_color * metalness + (BasePlasticReflection * (1-gloss) + MaxPlasticReflection * gloss) * (1 - metalness)

Both parameters BasePlasticReflection and MaxPlasticReflection are taken from params.xml

