The Senate and the House of Representatives are two houses of the United States Congress that share responsibility for lawmaking. Both of them were established by the US Constitution.
When the Senate and the House of Representatives pass different versions of the same bill, they are sent to Conference Committee. It is formed by members appointed from each house. The Conference Committee works to reach a compromise and when it finally does, they write a Conference report. This Conference report must be approved by the House of Representatives and the Senate. Afterwards, the bill is sent to the president for review. Once the bill is signed by the President, it becomes a law.