September 28 is the feast of St. Lorenzo Ruiz.
His feast day is September 28. He became a saint because he died the death of a martyr while working in the service of Our Lord.
Lorenzo Ruiz was martyred on September 29, which would probably been his assigned feast day. However, since September 29 is also a major feast day (The Archangels Michael, Gabriel and Raphael) his feast was set on September 28.
Feast day and memorial are, basically, the same thing. It is the day we celebrate the anniversary of that person's birth into Heaven.
St. Lorenzo Ruiz's birthday is believed to be around the year 1600, but the exact date is not known. He is honored on September 28th as the feast day marking his martyrdom.
Pope Benedict I is not a saint and has no feast day.
Saint Maria Goretti's Feast Day is July 6th.
The feast day of saint Mark is April 25.
Saint Laura's Feast Day is October the 19th.
Saint Helena's feast day is August 18.
The 23rd of April is the feast day of Saint George.
Saint Christopher's feast day is July 25th.