vibudhah pitaro ’surah
sargas te visva-srk-krtah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The creation of the demigods is of eight varieties: (1) the demigods, (2) the forefathers, (3) the asuras, or demons, (4) the Gandharvas and Apsaras, or angels, (5) the Yaksas and Raksasas, (6) the Siddhas, Caranas and Vidyadharas, (7) the Bhutas, Pretas and Pisacas, and (8) the superhuman beings, celestial singers, etc. All are created by Brahma, the creator of the universe.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
As explained in the Second Canto of Srimad-Bhagavatam, the Siddhas are inhabitants of Siddhaloka, where the residents travel in space without vehicles. At their mere will they can pass from one planet to another without difficulty. Therefore, in the upper planets the inhabitants are far superior to the inhabitants of this planet in all matters of art, culture and science, since they possess brains superior to those of human beings. The spirits and jinn mentioned in this connection are also counted among the demigods because they are able to perform uncommon functions not possible for men.