Chapter 17: Almonds= Token Against Rebels
The Lord speaks to Moses and tells him to take a rod (to represent each of the tribes of Israel) and place them in the tabernacle, writing the name of the princes of each tribe on the rod. The next day Moses goes into the tabernacle to find that, one of the rods had budded and was blooming almonds. They are commanded to keep it as a token against the rebels.
Chapter 18: Levites are called to Service
The Levites are called to minister in the priest’s office, and in the service of the tabernacle. Levites do not receive land inheritance like the rest of the congregation of Israel, but are supported by the tithes of the people. See verse 21 and 26.