Midterm elections in the U.S. differ from presidential elections primarily in terms of voter turnout and the positions contested. They occur halfway through a presidential term and typically see lower participation. These elections often focus on Congressional seats (both House and Senate) and can impact party control. Additionally, midterms tend to serve as a referendum on the sitting president's performance, influencing national and local agendas. The outcomes can shift the balance of power and significantly affect legislative priorities, making them crucial for political dynamics.