A few mixed facts about Mithraism and its difference to other “oriental mystery cults”
“Mithraism then entered Asia Minor, especially Pontus and Cappadocia. Here it came into contact with the Phrygian cult of Attis and Cybele from which it adopted a number of ideas and practices, though apparently not the gross obscenities of the Phrygian worship.” > LINK ( http://www.newadvent.org )
“In Antiquity, the Phrygian cap had two connotations: for the Greeks as showing a distinctive Eastern influence of non-Greek “barbarism” (in the classical sense) and among the Romans as a badge of liberty. The Phrygian cap identifies Trojans such as Paris in vase-paintings and sculpture, and it is worn by the syncretic Persian saviour god Mithras and by the Anatolian god Attis who were later adopted by Romans and Hellenic cultures. The twins Castor and Pollux wear a superficially similar round cap called the pileus.” > LINK ( http://en.wikipedia.org/wiki/Phrygian_cap )
“While it’s true that in his earlier incarnations, especially in Zoroastrian religion, Mithras was associated with the sun, no tauroctony is ever mentioned there or anywhere in pre-Roman Mithraic legends. Nor is there even the slightest hint in Persian accounts of Mithras killing some celestial bull. How is it possible, then, to reconcile the Mithras we see in Rome with his earlier synonymous counterparts?” > LINK ( http://www.usu.edu/markdamen/ )
Romanising Oriental Gods: Myth, Salvation and Ethics in the Cults of Cybele, Isis and Mithras (Religions in the Graeco-Roman World) by Jaime Alvar and Richard Gordon, 2008, pp. 385. > LINK
The difference between the cult of the Magna Mater (Attis, Cybele) and Mithraism is the most striking in the forms of baptism. Mithraism is a symbolic myth, whereas Magna Mater is an actual orgy cult, that uses blood in their initiation rituals > LINK
Finally:
You can’t really separate the the history of Mithraism from its Zoroastrian and Pre-Zoroastrian roots. Or you would end up losing the actual myth.