As per my understanding doping is a chemical process in which an atom replaced by an other atom and create defects in materials, while impregnation is a physical process in which atom added to the materials without replacement of any atom or ion and changes the property of materials.
Dear , doping is something we deal with adding impurities to the semiconductor to enhance the properties. Impregnation is forcefully adding for metal to another metal by sonication for long duration or stirring for long hour.
As per my understanding doping is a chemical process in which an atom replaced by an other atom and create defects in materials, while impregnation is a physical process in which atom added to the materials without replacement of any atom or ion and changes the property of materials.