Board Thread:Naruto Discussions/@comment-38792431-20200226192508/@comment-1512913-20200227064454

No, a technique's rank has nothing to do with its power, it only shows how difficult it is to learn. A C-rank Fire Release technique can easily overpower an A-rank Fire Release technique, granted user A has more powerful chakra, more chakra, better chakra control or combination of thereof.

That being, it doesn't mean Sasuke's Chidori is in any shape weaker than Kakashi's Raikiri, it just means that Kakashi's Raikiri is an advance on his original Chidori.