© brant

From wiki....

"Until the advent of helioseismology, the study of wave oscillations in the Sun, very little was known about the internal rotation of the Sun. The differential profile of the surface was thought to extend into the solar interior as rotating cylinders of constant angular momentum.^[4] Through helioseismology this is now known not to be the case and the rotation profile of the Sun has been found. On the surface the Sun rotates slowly at the poles and quickly at the equator. This profile extends on roughly radial lines through the solar convection zone to the interior. At the tachocline the rotation abruptly changes to solid body rotation in the solar radiation zone.^[5]"

Differential rotation is inferred from helioseismology(vibrations in the sun).

You can have current flow in the shell that would appear to be differential rotation..

Take the sun spots. If that is a current flow exiting the solar surface, the current flow can be precessing through the solid shell giving the appearance of rotation. There is a toroidal current flow in the shell (the solar conveyor) that is responsible for these phenomena...

 

"Solar physicist David Hathaway of NASA's Marshall Space flight Center in Huntsville, AL and graduate student Lisa Rightmire of the University of Memphis in Tennessee have been monitoring the sun using the Solar and Heliospheric Observatory (SOHO). They observe a massive circulating current of fire (hot plasma) within the sun operating at a faster pace as reported in the March 12th issue of Science. "

"The current of fire is a conveyor belt-like system called the Meridional Flow which rises to the surface at the sun's equator and spreads out toward the poles where it sinks back into the sun. "Normally it reaches peak speeds of about 20 mph," says Hathaway. "However, in 2004 the speed increased to nearly 30 mph and has remained that fast since.""

http://www.nasa.gov/topics/solarsystem/features/solar_plasma.html