Hannya is mask used in Noh (traditional Japanese theater) it represents a female transformed by jealousy and rage. Oni is an Ogre or demon like creature. Some humans can turn into oni but that's a very unique situation. The gods raijin and fujin are often depicted as oni. Oni also administer punishment in hell.

In traditional Japanese folklore, ghastly red-skinned and hideous demons called oni have long been thought to inhabit various parts of the world; they are usually depicted as humanoid in form but may have unnatural features such as an odd number of eyes, claws, fangs and face. 2 Onis Or Japanese Ogres Wear Clothes Made From Wild Animal's Skin.

Perhaps one of the most iconic images associated with Japanese art are devilish looking masks most notably of the Hannya, Oni and Tengu. These masks are often depictions of Japanese mythological demons and continue to be used in Japanese art, pop culture and even by many tattoo artists because of their distinctly fearsome and yet appealing
The difference between an oni mask and a hannya mask is the gender: oni represents a male demon whereas hannya is female. And unlike the hannya, the oni has a few varying origins. An oni could have come from: A vicious soul beyond redemption. A creature of hell passing down sentences. A soul of the dead.
Hannya and Oni are similar in that they have demon-like features. However, there are some physical differences between the two figures that set them apart. Hannya is typically depicted as having a white face with exaggerated red markings around the eyes and mouth. . 340 12 97 7 281 82 65 205

difference between hannya and oni