The requirement for the 5th generation included more range, more lethality and most of all more connectivity.
The 5th generation SPIKE LR2 increased the range to 5.5 km , improved, armor penetration in more than 30% , improved seeker technology by uncooled IR sensors and multispectral capabilities (data fusion of sensory data IR & VIS allowing a very strong target tracker and hot swap capability ( the ability to swap between sensors midflight allowing the gunner to easily detect camouflaged targets).
But the most dramatic capability of them all was the new ability for firing in non-line of sight scenarios (NLOS) based on embedded IMU enabling automatic navigation of the missile to target coordinates received from a third party (other force, UAV, drone or any other unit detecting a target) this capability does not exist in generation 1 to 4 and suddenly enabled the SPIKE teams to interact with other units and create a web or a matrix of sensors and effectors closing on targets rapidly without the need to maneuver in order to find line of sight to targets.