What Is The Difference Between The Gregorian And Julian Calendar. The gregorian calendar is very similar to the julian calendar, but it contains a few key differences. Since then, the difference between the gregorian calendar and julian calendar has grown to be 13 days, as the three years a.d.
The short answer to the difference between the julian and gregorian calendars is three days per 400 years. The basic difference between the two calendars is that the gregorian calendar is shortened by 0.0075 days in comparison to the julian calendar.