The projected points calculated for the draft summary uses your highest projected points for your total game opportunities. This would be considered your “optimal lineup” based on projection.
On the Matchup screen, your initial projection would be based on your first available games being used to fill your game opportunities.
You will be able to select which players are benched for certain game opportunities and the projections will update dynamically. You may choose to have someone play a certain game with a lower projection and the result would be a lower overall projection than what had been seen in the Draft Summary.