Final answer:
Different versions of a bill passed by the Senate and House are resolved by a conference committee, which negotiates a unified version for both chambers to approve; it then goes to the president for signature or veto.
Step-by-step explanation:
When the Senate and the House of Representatives pass different versions of the same bill, they must resolve the differences before it can become law. Often, one chamber will simply agree to the version passed by the other. However, if the differences cannot be resolved in this manner, the bill is sent to a conference committee, composed of members from both the Senate and the House, to negotiate a single version. Once both chambers approve the reconciled bill without further amendment, it proceeds to the president's desk for signature or veto. If the President vetoes the bill, a two-thirds majority in both chambers is required to override the veto.