• CEA- under FM, advices on financial matters, Eco Survey - basically just an advisor- a post to write and enjoy.
  Niti aayog- main work - strengthening federalism- also decides future policies ( such things are not decided by other 2 agencies) gives guidelines for better governance. It has become backbone of governance policy making. Also makes long term policies.
  EAC- its latest- work under PMO - ears n eyes on PM in financial matters. Since there were lot of issues where PMO needed its own body who has knowledge of Economy and PM can also hav independent thinking different from FM.
  

  • CEA works under FinMin and advises govt on purely economic matters.
    Niti Ayog advises on economic as well as other policy matters too.
    From vision magazines I understood, EAC collates information received from all the other sources and gives one best solution to the PM. It can suggest its own solutions too.