What's the difference between shia-sunni Nikkah procedures?

ASO! I wanted to know the actual difference between shia and sunni nikkah procedures. I belong to a sunni family and getting married to a shia boy. We don't have any problems with the witness issue. In sunni's (living in Pakistan) nikkah is preformed in Urdu language which makes sense for me, but through my research, I found out that shia nikkah must be said in Arabic language (either by both girl or boy, or by any molvi/imam). So my question is, if that's the case (shia nikkah has to be in Arabic), is there any authentic hadith or reference in Shia books or in Quran validating this point that **nikkah lines must be said in Arabic?** Why can't we just say the nikkah lines in Urdu, our native language? I'd like to hear from Shia side and their reference from any Shia Imam or from Quran with the source. Thank you!