Mr softer and setter

Mr Mark Softer - green label/cap with clear contents. Fairly aggressive decal softening solvent.

Mr Mark Setter - Blue label/cap with milky contents. A combination of decal softening solvent plus a mild adhesive which helps with decals which have insufficient glue (which can happen if the decals have been soaked excessively). I've found that this can often be used to apply decals directly to flat painted surfaces with minimal, if any silvering. The downside is that the adhesive can be pretty "grippy", making it difficult to reposition decals easily (you can apply a little water and re-float the decals to help reposition them) This can often leave a shiny residue on flat surfaces, which will need to be covered by a flat clear coat.

Either product can be used individually or in combination.

I am not familiar with that brand, but in most brands the setting solution is milder, just to help it snuggle down to the surface.  A decal solvent softens decal a LOT, helping it bend to sharp curves, compound curves, etc.  I would surmise that is what the "softener" is, but again, not familiar with those brand names.

Mr.hobby products.

similar to microscale products but noticeably stronger