From my experience there is a vast difference in the amount of effort that is required to smooth out wax sculptures versus sculptures sculpted with any of the polymer clays. The underlying principles and concepts are the same but wax, when cooled, is a much harder medium and thus requires quite a bit more work to achieve the desired result. Keep in mind that this is under the assumption that you smooth out your polymer clay sculptures prior to baking, which I have always done in the past. Some sculptors will bake their polymer clay sculptures and use wet sanding techniques for the final smoothing stages (this process will exponentially increases the amount of work needed to smooth out the sculpture).
The first step in the smoothing process is to clean up the sculpture by using various loop tools. Loop tools really are essential when sculpting with wax and the smaller loop tools can be used to help blend shapes together and smooth out some of the hard lines in the sculpture. I do not strive for perfection at this stage since I will later on incorporate other processes to smooth out the piece.
Once we are done with the loop tools the next step is smooth out the wax even more by using odorless mineral spirits and a stiff paint brush. I would associate the use of odorless mineral spirits as the same reasoning for using 90-99% alcohol on sculptures created in polymer clay. Odorless mineral spirits dissolves the top layer of wax but unfortunately does not work as well on wax as alcohol does on Super Sculpey (a lot more time needs to be invested smoothing out the wax as compared to using alcohol on polymer clays). The key is to start out with a very stiff brush and over time work towards using a softer brush. The stiffer brushes are used for breaking down the rough shapes and tend to give the sculpture a soft matted look. The smoother brushes smooth out the matted look and help to start moving the sculpture towards a more polished looking piece. Also keep in mind that while working with odorless mineral spirits a wax residue will build up on the brush so you will need to use a paper towel or rag to periodically clean the brush.
If your sculpture still needs additional smoothing then the next step is to use fine sandpaper. Sandpaper is not always necessary but there are times when I can’t quite get the area as smooth as I would like with just the odorless mineral spirits. The key to using sandpaper is to put the sculpture in the freezer for about 10-15 minutes before moving on to this step (follow safety precautions since you are placing chemicals in the freezer (i.e. residue for the odorless mineral spirits). This helps harden the sculpture for sanding and really helps if you wet sand the wax pieces (an example of wet sanding is sanding the sculpture while running water over it from a faucet). If you choose to not wet sand the piece then you will most likely need to do a quick cleanup using a soft brush and odorless mineral spirits after the sanding is complete.
The final step in the smoothing process is to use a wet rag on the sculpture. If you had recently used odorless mineral spirits on the sculpture then you will want to let the piece sit for a bit before moving on to this step. Odorless mineral spirits can make the top layer of the wax a little tacky so it is best to set the sculpture aside awhile so that the wax can get back to its original state. Once the sculpture is ready, apply the wet rag to the sculpture with the same approach as you would use to for sanding the piece. This process does take some elbow grease but once complete the sculpture will have a smooth surface with a nice sheen to it.
So in conclusion there is a lot more work involved with smoothing out wax versus polymer clays such as Super Sculpey. The overall process really is not that hard, it just takes time, patience and some experience to get the desired results.