President of the Senate (Australia)
The position is provided for by Section 17 of the Constitution of Australia. The Senate elects one of its members as president at the start of each new term, or whenever the position is vacant. This is usually—though not necessarily—a member of the party or coalition that holds the most seats in the Senate. The largest party in the Senate is not always the governing party, as government is determined by the House of Representatives. The President of the Senate and the Speaker of the House of Representatives may consequently be from different parties.
Leader of the Government in the Senate (Australia)
The Leader of the Government in the Senate (historically also known as the Leader of the Senate) is the most senior cabinet minister in the Australian Senate. The title is given to the leader of the governing party (or the largest party in a governing coalition), irrespective of whether the government has a majority or plurality in the Senate. His or her Opposition counterpart is the Leader of the Opposition in the Senate.