I'm quiet confused in reading literatures involved MHD turbulance and Alfvenic turbulence, it seems they are pointing to the same notion in most of the content. Please explain the difference of them?
MHD turbulence refers to a nonlinear state of the MHD equations, whereas Alfvenic turbulence refers to a nonlinear state of equations that describe Alfven waves. MHD turbulence can be Alfvenic turbulence, since MHD does describe shear Alfven waves. However, fluid or kinetic models more general than MHD can also describe Alfven waves and thus Alfvenic turbulence.