Parliamentary Debate is a two-person debate event featuring two sides to an argument, one being the government and the other the opposition. The government supports the motion (topic of debate), discussing a specific issue and solution in the topic area. The other side, the opposition, finds weaknesses in the government's argument. Parliamentary Debates discuss current issues, government laws, and other relevant topics.
Video #1: Sample HS parli debate competition
Video #2: Parliamentary debate explained
Link: National Parliamentary Debate League website
Congressional Debate is an individual debate event and a mock legislative assembly competition where students draft bills (proposed laws) and resolutions (position statements). They and other students present speeches on various sides, ask questions, and then take action by voting for or against the legislation. (https://www.speechanddebate.org/wp-content/uploads/2017-Congressional-Debate-Guide.pdf)