Kakashi's "original" technique
Any Naruto fan remembers the epic scene where Kakashi, the copy ninja faces off against Zabuza of the hidden mist and says that he will now use his "one and only original attack". He then precedes to unleash his "lightning blade" or Raikiri
For hundreds and hundreds of chapters, people have worshiped this amazing jutsu (which gave birth to many variations of the technique created by sasuke) under the guise that Kakashi created a true masterpiece. I myself was astounded by this jutsu seeing as I am an incredible Kakashi fan.
Unfortunately, (anyone not caught up in the manga through the 4th shinobi war and the kages vs kages fight please leave) we now know that this move isn't as original as we all once thought
When the third Raikage faces off against the allied shinobi forces, he uses an attack named something like the hell finger technique or something. Anyway, it involves him building up an enormous amount of lightning chakra in his hand, straightening his fingers, and spearing through an opponent. Knowing that the third Raikage was well before Kakashi's time, it is clear that the Raikage developed his move first.
I have to say though, there are some key differences between the moves.
1st) Kakashi uses enhanced speed to increase the power and piercing strength of his attack. Unlike the 4th raikage whos main attribute is his speed, the 3rd raikage was known for his rock-hard body (literally). While i wouldn't call him slow, I wouldn't put him at levels even close to his son, and think that he probably is less fast than kakashi (who along with sasuke had to attain speeds greater than rock lee in the chunin saga just to use his jutsu).
2nd) Raikiri has something special about it that seperates it even from chidori. When sasuke first used his chidori, it was simply a mass of lightning in his hand. Kakashi's full fledged raikiri was super concentrated in a small pointed ''blade'' enveloping kakashi's hand. I believe a crucial difference between lightning blade and the ''hell finger thunder punch" or whatever is that kakashi has his lightning much more concentrated. Think about it, the people of the hidden cloud seem to be able to use lightning like is the air they're breathing. there isn't a while hell of a lot of chakra consumption. Kakashi seems to get tired after a few uses of lightning blade. Its clear that kakashi's lightning takes a lot out of him, so rather than using lightning in bulk, he puts a small amount of it where it counts.
All this taken into consideration, obviously the raikage's rendition is more powerful (seeing as he could use it to take out several shinobi) but we do not even know if he could do this attack multiple times under non-edo circumstances. I guess we can call raikiri the 'economical' alternative that kakashi created for himself.
Thats about all i have to say comparing kakashi's lightning cutter to the raikiri's attack, but there are some few odds and ends i'd like to contemplate: Would kakashi's attack become stronger if he only used one finger like the raikage? Also, was the war in which A and B fought minato the same war that kakashi had fought in? Because by the time the war started, 12 year old kakashi had ALREADY developed his attack. I doubt that he saw the raikage use his version, so i'm not saying that he cheated, but we know that (based on how A and B look and minato look) the raikage perhaps didn't die for at least a couple years. Is it possible that he saw/heard of kakashi using the attack during the war and created his alternative shortly before his death? Then again, he used the attack against the 8 tails BEFORE Bee was his jinchuriki, so i guess that would pre-date kakashi (is Bee older than kakashi?). Too many questions too little time. If you guys have any light to shed on this, i'd love to hear it.