Geologists use the term mass movement to refer to any downslope transport of rock, regolith (soil etc), snow and ice. In all cases gravity is the principle factor that causes the land to slide or slip. Of course there must be a plane of weakness, caused by instability in the rocks, lubrication by flood water or ice, but it will not move at lall unless the pull towards the earth is less than the pull downslope.
Mass movement is distinguished by the velocity of the movement, the characteristics of the mass, the type of material the mass is composed of and the environment in which it takes place.
Landslip suggests something less devastating than landslide - and is a commonly used layterm for creep, solifluction, slumping or glacier flow.
Landslides in fact are the correct term regardless of speed or distance. Creep occurs when a hill is frozen and rethawed each year - the slope is unstable and the rearrangement of soil particles on each thaw over the whole area slowly moves the surface of the land down hill.
Solifluction is saturated ground that slips in wet slumps. Glaciers move in two ways either from basal sliding due to melting or by creep where the ice moves from the middle up, the bottom frozen to the rock.
Slumping is another form of mass movement when a mass of regolith detaches and slides down hill. This can be a few metres or kilometres. Mudflows and debris flows occur when heavy rain flushes away in massive floods unstable regolith.
Landslides refer to sudden movement of rock down a non-vertical slope and can be made of rock or regolith (debris slide). This occurs when the rock or regolith is unstable and detaches from the slope at a plane of failure on the same angle as the slope. Rock falls on the other hand occur on a vertical slope.