During the process of filtration, the insoluble solid left on the filter is called RESIDUE
while the liquid which passed through the filter is called filtrate.
Decantation involves separating a liquid from a solid by POURING the liquid, called the supernate, from the MIXTURE without disturbing the solid residue.
Filtration involves pouring a solid-liquid mixture (suspension) through a PIECE of filter paper or other porous material to separate the solid from the liquid.