Verse 14 “And this day shall be unto you for a memorial; and ye shall keep it a feast to the LORD throughout your generations; ye shall keep it a feast by an ordinance for ever.”
The meal eaten at the time that Jesus instituted His memorial Supper (the Lord’s Supper) was not an observance of the Passover meal. The Lord’s Supper was simply one of the meals eaten by Jesus and His disciples during the week of Passover. The Passover lamb would have to be killed on the 14th day of Nisan, the day on which Jesus was crucified and placed in the sepulcher, the “Preparation Day.” The Passover meal would be eaten at mid-night after the “Preparation Day.” The Lord’s Supper was obviously instituted at least one day prior to the preparation day. So the timing of these events does not allow the conclusion that the Lord’s Supper and the Passover were one and the same.
Furthermore, there are stark differences in the details of the two meals. There is no mention of the disciples eating lamb at the meal where Jesus instituted His supper. The lack of any mention of a lamb would have been an omission that would be hard to understand if the meal was the Passover meal. And at the institution of the Lord’s Supper there is no mention of bitter herbs, or of the disciples eating standing up with their shoes on their feet, or of them having staffs in hand as they ate, all of which would have been the case if the occasion were the Passover meal.
The only similarities between the two meals are that both meals symbolized the Lord Jesus Christ. These are extremely important similarities. The Passover looks forward in prophecy to the sacrifice of Jesus, and the Lord’s Supper looks backward in history to the same event, the crucifixion of our Lord. The greatest of all events is pictured in two meals, God’s Lamb for sinners slain.