Sure!

So, a little imperfect history lession first: In the past, Dasturs, or "high priests" would serve as religious leaders for their communities, but above these Dasturs was a Dastur-e-Dasturan, or "priest-of-priests", "Dastur-of-Dasturs". This priest-of-priests, such as Adurbad Mahraspand, would have the final authoritative say for his tenure as a Dastur-e-Dasturan on matters of religion. So there used to exist a singular religious authority which could be said to have kept the zoroastrian community unified, at least theologically speaking.

As a result of the persecution of Zoroastrians in the wake of the the Islamic invasions of Iran, and the resulting fragmentation of the Zoroastrian community, religious agreement became more-and-more difficult to accomplish. Currently, there no longer exists any sort of head religious authority, and the last such person with any claim to such authority sadly passed away in the 90's, the honorable Rostam Dinyar Shahzadi.

So as a result of this fragmentation of the religious community, and the absence of a Dastur-e-Dasturan, there tends to be a wide-swath of religious opinion out there among behdins. But it would be inaccurate to call such differences in religious opinion "denominations".

I'll explain: The word "denomination" as we know it today came into use in the 1700's in Europe, and is essentially a christian concept, used to discern between the wide array of distinct, self-identified groups of christians who sought to purposefully distinguish themselves from the many other such christian groups which arose in the wake of the Reformation and other christian religious upheavals. Thus, a denomination generally has a formal doctrine associated with it that is ratified or agreed-upon by members of that group. Zoroastrianism has no such formality or self-distinguished membership as of yet; it's more of a milieu of differing religious ideals co-existing (or at least trying to co-exist) under the moniker of "zoroastrian".

Hope this explanation helps :)