The soft silicone material on the left has painted on eyebrows and stick on eyelashes. The hard silicone material on the right, has implanted eyebrows and implanted eyelashes.
The reason for this is because the harder material has an easy time holding the tiny hairs in place. This is also true when implanting hair on top of the doll’s head. The softer material can not hold hairs in place properly so it is not an option to have implanted hair with a soft silicone material.
On the other hand, soft silicone is soft enough to provide an oral function for the doll head and hard silicone is too hard to allow for an oral function.
Both materials have pros and cons. Pros of hard silicone is a much more realistic look and implanted hair adds even more realism. Hard silicone also allows for longer lasting make up on the doll’s face. The con for hard silicone is that it does not offer an oral option.
The pro for soft silicone is that it does provide an oral function. The cons for soft silicone is that it is less realistic because it lacks the implanted hairs along with the overall look being less realistic.