Up to 20 meters long and weighs approximately 50 tonnes
It is similar to the sperm whale that exists today, but the difference is that these two are aggressive predators with teeth on both the top and bottom.
Megalodon was superior in maw size and bite force.
Leviathan’s speed is superior
Leviathan is superior in intelligence as a mammal.
Overall, it seems like Leviathan has the upper hand.
Megalodon seems to be more dangerous if it gets hit once.