[Exodus 12:18-19 NLT] (18) The bread you eat must be made without yeast from the evening of the fourteenth day of the first month until the evening of the twenty-first day of that month. (19) During those seven days, there must be no trace of yeast in your homes. Anyone who eats anything made with yeast during this week will be cut off from the community of Israel. These regulations apply both to the foreigners living among you and to the native-born Israelites.
[Leviticus 23:5-8 NLT] (5) "The LORD's Passover begins at sundown on the fourteenth day of the first month. (6) On the next day, the fifteenth day of the month, you must begin celebrating the Festival of Unleavened Bread. This festival to the LORD continues for seven days, and during that time the bread you eat must be made without yeast. (7) On the first day of the festival, all the people must stop their ordinary work and observe an official day for holy assembly. (8) For seven days you must present special gifts to the LORD. On the seventh day the people must again stop all their ordinary work to observe an official day for holy assembly."
Is this a contradiction? A change? Did the feast of unleavened bread begin on the 14th or 15th?