As nouns the difference between touchdown and landfall
is that touchdown is (american football|canadian football) a six-point score occurring when the ball enters possession of a team's player in the opponent's end zone analogous to a try in rugby while landfall is arrival at the shore by ship.
As nouns the difference between landslide and landfall
is that landslide is a natural disaster that involves the breakup and downhill flow of rock, mud, water and anything caught in the path while landfall is arrival at the shore by ship.