I believe HT tends to do idealized portraits, that they make their sculpts symmetrical even if real people all have asymmetrical faces. I remember seeing a photo of an HT sculptor using a mirrored photo of Carrie Fisher as reference for their first Leia.
One thing I like about HT is that they cast in a semi-transparent, molded-in-color plastic, making the heads look softer, more organic and of course, realistic. I think these 3rd party heads (like Iminine's) are molded in opaque plastic, that they reveal the imperfections of the original wax sculpture.