All Saints Day is for the celebration of saints and martyrs like the article said. All Souls Day is the day of remembrance and prayer for all departed souls.
In my church, for All Souls Day, everyone gives the names of their departed family and friends which are read aloud and then we pray for them.
I'm sure different churches organized slightly different services on these days though. These practices also differ from country to country. I have a friend from Spain and she was telling me that All Saints Day is a very important day in Spain and it's a public holiday.