They're similar moves, but with different range of motion. Deadlifts are the heaviest move I listed and it works the abdominal muscles via isometric contractio

They're similar moves, but with different range of motion. Deadlifts are the heaviest move I listed and it works the abdominal muscles via isometric contraction, which is considerable tension at very high weights. I'll cede that deadlift is more similar to an abdominal plank than a sit-up.