” What are the chief differences between the EMP and Carrington?”
EMP is typically what is referred to as the effect from a high altitude nuclear detonation.
A “Carrington Event” is a solar storm that causes a geomagnetic disturbance.
EMP top frequency is about 1000MHz, a Solar EMP/Geomagnetic Storm has a top frequency content of a few HERTZ.
A geomagnetic storm causes Geomagnetically Induced Currents - which when imposed on long-distance transmission lines can cause uncontrolled DC currents to superimpose onto the AC transmission line currents which is the mechanism for transformer damage.
What I wonder is how man fires would break out. During the Carrington Event a number of Telegrapher offices caught fire. Now every house and building is wired to the grid.