Another commonality with these feasts is that they are both kept for seven days. That may sound obvious, and it is, but it is worth reviewing God's commands so we don't forget. Back in verse 6, it says, …seven days you must eat unleavened bread. You don't have to turn to these, but I will read to you the same command in other places:
Seven times, God says to eat unleavened bread for seven days. He is very clear.
It is commonly held that Unleavened Bread is about putting sin out of our lives. And while that is an aspect, if we were to go through all of God's instructions for Unleavened Bread, we would see that His reason and emphasis are different. What God overwhelmingly emphasizes is His deliverance, not our work of avoiding leavening and thus sin (Exodus 12:17; Exodus 13:3, 8-9; 23:15; 34:18; Deuteronomy 16:3).
The overarching reason for that feast, and the reason we eat unleavened bread for seven days, is to remember God's deliverance. When we get to the New Testament, Jesus identifies Himself as the bread of God - the bread of life. He was entirely unleavened.
Further, Paul tells us in I Corinthians 5:8, Therefore let us keep the feast, not with old leaven, nor with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth. Christ is the embodiment of sincerity and truth. He is the One who delivered us from this present, evil age, from spiritual bondage, from the power of darkness. And it is through the strength that He supplies that we have the means to overcome sin. And that strength comes from ingesting His word and beseeching Him to live His life in us every day.
The unleavened bread that God says we must eat for seven days represents Christ Himself. To miss eating the unleavened bread of sincerity and truth is to miss out on the divine connection with our Savior. Our minds should rebel at the thought of skipping that.
It is similar with Passover. The bread and wine are the symbols of Passover. It wouldn't be Passover without them. These things may just be symbols, but these symbols signal to God our intent and our desire to fulfill all righteousness, even in the symbols.
In the same way, we keep the Feast of Unleavened Bread for seven days by eating unleavened bread each day and not merely avoiding leavening. Consider what neglecting to eat the unleavened bread of life every day would signal to God. The symbols matter.
Faithful and righteous Daniel chose to spend the night in a cave of lions rather than give up his bread of life for a single day. That's how important his connection with God, and being strengthened by God, was to Daniel. It is those who know their God who will be strong and carry out great exploits, but that strength and knowledge of God come from continually partaking of what, or of Whom the unleavened bread represents.