TITHE VS FIRSTFRUITS
Nehemiah 10:37 (KJV)
37 And that we should bring the firstfruits of our dough, and our offerings, and the fruit of all manner of trees, of wine and of oil, unto the priests, to the chambers of the house of our God; and the tithes of our ground unto the Levites, that the same Levites might have the tithes in all the cities of our tillage.
In Nehemiah 10:37 we learn that the firstfruits were taken to the temple for the priests, and the tithes were taken to the Levites who lived in the Levitical cities. Therefore, we see that firstfruits have nothing to do with the tithe.