MATLAB: How is (-2)^(2/3) different than ((-2)^2)^(1/3)

complexexponentialnegative

Hi everybody.
It's the first time I ask a question here.
I would like to understand how is that possible that the following expressions give different results:
>> (-2)^(2/3)
ans =
-0.7937 + 1.3747i
>> ((-2)^2)^(1/3)
ans =
    1.5874

 +2^(2/3)                     =  1.5874 -1/2^(1/3)+3^(1/2)/2^(1/3)*i = -0.7937 + 1.3747*i -1/2^(1/3)-3^(1/2)/2^(1/3)*i = -0.7937 - 1.3747*i
 4^(1/2) = ((-2)*(-2))^(1/2) = ((-2)^(1/2))*((-2)^(1/2))