After you file

This tax year has been a nightmare..,filed my taxes 2/1/18 got so called accepted same day..today is 3/31/18...over the last month and a half I had to do ID verification and another waiting game...talk to irs again yesterday and was told my taxes are under review and a letter was sent out to me explaining details on 3/28...have not received that yet..also said that my taxes will start being processed April 9th and can take 45 days before DDD....but I was assured that I was not being audited...lol...what's the different?