In the federal Congress of the United States, the roles of the House majority leader and the Senate majority leader differ slightly. At the state level, the majority leader of a given state legislative chamber usually performs a similar role to that of their federal counterpart.
Thus, the majority leader is seen as the de facto leader of the Senate, especially in modern times, and thus, in accordance with Senate rules, the presiding officer of the day gives the majority leader priority in obtaining recognition to speak on the floor of the Senate and they determine which bills get voted on. The majority leader is seen as the chief spokesperson for their party in the Senate.[1]
In the House of Representatives the majority leader's presence and power often depends on the session. In some sessions, the majority leader takes precedence over the speaker as House leader and legislative party leader either by force (which usually occurs when the speaker of the House is unpopular) or because the speaker of the House voluntarily surrenders power to the majority leader. In most sessions, the speaker of the House takes precedence as house leader and party leader, with the majority leader being irrelevant and largely powerless outside the fact they might be speaker of the House one day. Except, of course, for the fact that the majority leader (as well as the speaker and the minority leader) are the only members of the House that can speak on the floor for an unlimited amount of time and cannot be interrupted by the chair.