Fantasy league format in which the teams remain the same each year. Instead of drafting a new team each season, you keep the same team from the previous season, while drafting rookies and players not currently on teams.
A league in which you keep your entire roster from year to year. The next season a draft is held to improve your team. Usually the draft order is based on the previous year's finish. Dynasty leagues are a long term commitment.
A league in which you keep your entire roster from year to year. The next season a draft is held to improve your team from any players or rookies not already on a roster. Typically a long term commitment.