Unlike all other Western Iranian languages, Tati has got an interesting phonetic feature called rotacism: the Iranian d turns into r after a vowel. Among other phonetic traits of the language we can call the preserved initial v (other Iranian languages have b). As for the grammar, Tati does not know enclytic pronouns, several secondary verbal forms which cannot be conjugated. The southern dialect was restructured somehow and became morphologically and sintactically much like Azerbaijani. This Azerbaijani influence is the main distinguishing feature of Tati which makes it different from other Iranian tongues.
The Tati literature language is used only in northern dialectal forms, but still does not have exact norms, orphographical and morphological. And the majority of Tats use Azerbaijani or Russian as their literature language.