How can they just replace something in the bill passed by the house without the house approving that change? Would that not constitute an amendment? My understa

How can they just replace something in the bill passed by the house without the house approving that change? Would that not constitute an amendment? My understanding of the bicameral legislature is that both bodies need to clear the exact language of potential legislation for it to become law. Any change made by either body constitutes an amendment and needs to be approved by the other before the president can sign the bill into law or veto it.