Morphs are similar in many ways to the criminals that they are hunting. They have strong coping mechanisms for insulating their emotions from the horror that they are exposed to, allowing them to transition from one case to another easily. The term Morph comes from the fact that they they can take their emotions and convert them into something else. In doing so, some Morphs dehumanize both their victims and themselves to a degree. Randal Alpert is an example of a Morph. Robert Backus is an extreme example of this type; he dehumanized himself and everyone that he came in contact with.
Empaths are more inclined to identify with (or empathize with) the victims of crimes and take on the emotional burden of seeking justice for the dead and their loved ones. They internalize these feelings as a way of fueling their drive to solve the case. Empaths are more likely to be relentless in pursuit of killers, but the downsside is that they suffer when they are unable to solve a case. Terry McCaleb and Harry Bosch are examples of this type.
Walling said that it is healthier to be a morph, or at least easier. She cited the cases of Janet Newcomb, Jon Fenton and McCaleb as examples of Empaths who could not endure the emotional strain, but at the same time could not pull themselves away from the work.