Why is this night different from all other nights?

In the early Christian church, the celebration of Easter was called "Pasch". This comes from the Hebrew word meaning to "pass over", and the Passover commemorates the Exodus, the liberation of the Israelites from Egyptian slavery as described in the Book of Exodus. The Feast of Passover marks the deliverance of the Children of Israel by God from their slavery in Egypt under Pharaoh.
The name Passover derives from the night of the Tenth Plague, when the Angel of Death saw the blood of the Passover lamb on the doorposts of the houses of Israel and "passed over" them and did not kill their firstborn. The Passover meal of roasted lamb, unleavened bread, and wine commemorate this event.

Passover was God's greatest saving act in the Old Testament, and it became Israel's greatest festival and feast. This was a special night, a night to be remembered, a night different from all other nights.

When Jesus and His disciples came together in the upper room to eat what is now known as the Last Supper, they were celebrating the Passover. It was a special night for the disciples, to be sure, for they were sharing a special meal with their Master. But they didn't realize how truly special it would become. For while they were eating Jesus took bread, gave thanks, and gave it to them saying, "Take and eat; This is my body given for you. Do this in remembrance of me." And after they had eaten, at the time of the Cup of Blessing, which represented the blood of the Paschal lamb, Jesus took the cup, gave thanks and said to them, "Take and drink, this is my blood of the new covenant for the forgiveness of sins. This do as often as you drink it, in remembrance of me."

Jesus Christ Himself was the true Paschal Lamb who would shed His blood and die on the cross to take away the sins of the people. As we celebrate the Lord's Supper on this special night, we receive His body and blood for our forgiveness and salvation, and we proclaim our Lord's death until He comes again.