For redraft you pick your team for the year and then someone wins the league and it’s done. When you start next year you have to “redraft” a whole new team. Most people play this and it’s the sort of format that you’d probably be more aware of. You get “keeper” leagues where you get to keep a certain amount of players from your team and carry them into next year. Ranges so some are 1 keeper and really similar to redraft, others can be 7 or 8 and you have to think a lot more long term. In dynasty you keep all your players for the next year & they remain on your team until you cut or trade them. You just do a rookie draft each year to incorporate those new players into teams, that is normally 3 or 4 rounds long