Classic contests are multi-game slates where participants can complete their lineup from a number of different football games. The roster format for classic contests requires you to fill 5 positions:
Showdown is a single-game contest where the rosters will have a CAPTAIN position, which gets a 1.5X fantasy score multiplier, and FLEX positions. FLEX means players from all positions are eligible for that slot.
For Reignmakers football, Showdown slates will typically be available for all primetime games each week (TNF, SNF & MNF).
Note: CAPTAIN is also a "FLEX" position.