Solar flare EMP can take down some the power grid but a nuclear EMP will destroy not only that but most of all electronic devices. Can you imagine the suicide rate in the country once folks realize their smart phones are dead forever?
Reminds me of the scene from the TV show “Jericho” where the kids were using dead cell phones for stickball.
Nuclear emp effects require long lines to attenuate the voltage surge.
A few of the declared nuclear powers have the capability to possibly do some damaged on a regional basis but cars, generators, small electronics are not going to just be zapped/
An extreme solar flare like something that happened in the 1870’s would affect the whole world. The damage would be extreme just like a man made EMP event only on a wider scale.