There are types of material whose prime function is not the separation of solid particles from fluids, but in whose use such separation does occur. They operate by different physical processes from filtration (and from each other), and are used for different purposes.
“ABSORPTION” is the process in which a fluid is dissolved by a liquid or a solid (absorbent). However, in some cases, there is absorption operation by the chemical reaction.
“ADSORPTION” is the process in which atoms, ions or molecules from a substance (it could be gas, liquid or dissolved solid) adhere to a surface of the adsorbent.