To my knowledge,
skip: one foot touches the ground
jump: both feet are off the ground
hop: both feet are off the ground
Note, for some speakers, jump rope and skip rope mean the same thing. Either both feet or one foot is off the ground.
Note, the difference between hop and jump has to do with, I believe, two factors: recursion and/or height, the relative distance between feet and ground.
Happy New Year! :smilcol: