Board Thread:Episode Discussions/@comment-25319479-20171206103000/@comment-9782468-20171211155117

Elveonora wrote: They are the same technique, just different names for it, with Chidori being the original name and Raikiri the nickname if you will.

Just for some reason, Raikiri is labeled as an S-rank technique, while Chidori as an A rank technique. This might be nothing more than an error, or it simply refers to the refinement that Kakashi has made to Chidori over the years, meaning that the base technique is an A rank, but super-focused version of it or whatever is S rank or whatever. Yeah, I could never find a reference in the manga that said Raikiri was the stronger counterpart, I only remember Guy saying that Raikiri was another name for the technique, Chidori. So I just assumed that the info was grabbed by a translator from one of the databooks.