as people in haunted houses, or study demonology can tell you demons (inhuman hauntings) come in two basic forms.
animal like and humanoid like.

the humanoids are roughly human shape, the animal like tend to be dog, cat, or some other animal. both vary a great deal in size.

this thread asks for its discussion, are these different things? are they related or are the same things only chaging shape, or are they as some suggest that the animal like ones are actually animals from these other dimensions or etherial creatures that are encountered while the humanoids are sentient inhuman spirits/demons?