To quantify the difference in nuclear and neutron bombs, one leaves behind a radiation footprint similar to Chernobyl. The other, the neutron bomb allows an occupying force to re-enter the detonation zone at a period of six weeks without danger to humans. The buildings can be used again. But with a nuclear bomb you can create a radiation zone or belt that makes it impossible to traverse if only 200-miles wide without the humans dying. Both bombs create radiation that kills within 1-4 days. The beauty of the neutron bomb is that it can be fired from artillery and is very small compared to nuclear delivery systems.
An alternative history to the Sam Cohen story?