Undigested food is that portion of the food which is not completely digested after the process of digestion. Sometimes the food containing high fibers may not be completely processed/digested and thus remains as undigested. This usually happens in the case of fibrous food or food containing roughage.
Metabolic waste or human waste is the human excreta is the waste produced as a result of the bye products of the process of digestion. After the process of digestion is of the waste material is released from the body in the form of excreta [feces and urine]. It includes nitrogen compounds, water, sulfates, etc.
Undigested waste cannot be called as metabolic waste, as they do not undergo the process of digestion.