A bill must pass both houses of Congress before it goes to the President for consideration.
Though the Constitution requires that the two bills have the exact same wording, this rarely happens in practice. To bring the bills into alignment, a Conference Committee is convened, consisting of members from both chambers. The members of the committee produce a conference report, intended as the final version of the bill. Each chamber then votes again to approve the conference report.
Depending on where the bill originated, the final text is then enrolled by either the Clerk of the House or the Secretary of the Senate, and presented to the Speaker of the House and the President of the Senate for their signatures. The bill is then sent to the President.