Earth's Highest Mountain: Mount Everest = 29,029 ft
Earth's Deepest Ocean Canyon: Challenger Deep = - (-)36,070 ft
Total Difference ----------------------------------------------------- 65099 ft
Mars' Highest Mountain: Olympus Mons = 69,650 ft Mars' Deepest Ocean Canyon: Valles Marineris = - (-) 23000 ft
Total Difference ----------------------------------------------------- 92650 ft
ANSWER: Mars has greater difference of Highest Mountain - Deepest Ocean Canyon. It differ with that of Earth's by 27, 551 ft