It's surprising if there really is a difference for such a basic word.
(H. nemɔntɔnno (in writing, the tatsɔmo form "nimɔntron" is preferred) vs M. daoat)
But, speaking from my Hindi sense, Dib jii, aren't nimantran and daavat two different words, viz. invitation and feast, respectively? Or does "daoat" mean invitation instead of feast in Bengali?
Dib: Does jaul have any religious significance (like some of the other words you have mentioned might)?