While the MOVEMENT is essentially identical, sliders will be a regression and taps/however will be a progression of the movement. Both are part of my lower extremity rehab progressions to get people comfortable with single leg movements. Single leg movements are the GOAL for lower extremity rehab.
I cue people with sliders to pretend there is an eggshell under their toes to minimize the amount of "push" through the sliding leg. However, the benefit of sliders >> taps is that for someone who doesn’t have the adequate single leg control/strength yet, you can give them extra assistance by pushing through that sliding leg more OR simply it gives them another point of contact from a balance prospective. You can slowly increase the amount of assistance (ie load the slider leg starting with 30% weight to 5% weight) as someone gets stronger/more skilled at the movement.
I'm using valslides (which are expensive). You can EASILY perform the same exercise with furniture movers. Furthermore, you can put a magazine on carpet or a pillowcase on hardwood/linoleum floors.
When it comes to direction:
⬆️Anterior --> more quad
➡️Sideways --> more frontal plane adductor/abductor