When the house and senate passed substantially different versions of a bill, a senator can convene a Conference Committee, which is a temporary panel composed of senior members of both chambers, called "managers", and appointed by presiding officers of the Senate.
In the Conference Committee, representatives of each chamber work together to reconcile their difference in order to reach a compromise. if a compromise is reached, the managers prepare a conference report and then they send it to each chamber. Once the conference report is approved by the chambers, the bill is sent to the President for signature and becomes a law.