Most of the differences are creative or gameplay differences, there are some things GTA 4 definitely does better, and others GTA 5 definitely does better. All in all the situation is not the same as Far Cry 2 vs Far Cry 5 or Dead Rising 1 vs Dead Rising 4, those games have glaring and shocking differences in the underlying fundemebtal physics simulation itself.
I agree, my point was only about the GTA video.