RSI vs. CCI

is there a major difference between the CCI and RSI? they seem pretty much the same, except one shows oversold/overbought ratings at different numbers, but other than that they seem pretty much the same.

 

all indicators point out the same thing eventually, how each trader use it make all the diff.

 

I may be mistaken since I do not use them and I have not studied them in years, but do not all "oscillators" essentially tell you the same thing and at about the same time? As I understand it, depending on your choice of the "look-back" period, you can make just about all of them sing in harmony.