The 706 is to report the value of the estate. This is only required if the estate is taxable (over 1.5MM)
The 1041 is to report the income of the estate during the administration period. This would be required of the estate generated income in excess of $600 or had capital gains/losses.
Sometimes you need to file both. Sometimes you need to file neither and sometimes it is one or the other. If you could provide more details about what specifically you are trying to report, I can help you better.