What's the Difference Between the Old Testament and the New Testament?

The story of zechariah son of jehoiada from second chronicles 24, to illustrate the murderous impulse of the pharisees and the religious leaders. If there were no such oratory device being employed here, that message still very much comes through. And maybe what he's doing in this is intentionally referencing two prophets at the exact same time who had the same name. They were pointing to exactly who christ is and god's redemptive work through him.