I was asked the difference between All Saints and All Souls days and I had to pause. I gave an answer, which was deemed unsatisfactory by the questioner. I also thought I was somehow missing the mark a bit, so I decided to do some research.
All Saints Day is a solemnity and a holy day of obligation. The Church has set aside this day to honor all the saints, both known and unknown who are in heaven.
All Souls Day is celebrated the day after All Saints, on November 2. This day is for all those who have died but are not yet in heaven.
For more information:
All Saints Day
All Souls Day