Noha is a genre of Arabic, Persian, or Urdu prose depicting the martyrdom of the Holy Imams. Strictly speaking noha is the sub-parts of Marsia. Nohas are usually poetry expressing the sorrow felt by Shia Muslims for their leaders. People who recite Noha are known as Noha Khuwan.
Naat is a poetry that specifically praises the Islamic prophet Muhammad. Many of the famous scholars in the earlier days of Islam wrote Naat. People who recite Naat are known as Naat-Khuwan.