In the promotion and relegation model, used in leagues like the English Premier League, teams move between divisions based on performance—top teams in lower tiers are promoted to higher divisions, while the worst-performing teams are relegated to lower divisions.
The franchise model, used in leagues like the NBA, NFL, and MLB, features a fixed set of teams year-on-year, often with revenue-sharing and salary caps. Entry to the league is only possible with relocation, or when a new team is added.