The isosurface of Vortex with Q criterion
 

When I calculate the vortex region with Q criterion by Tecplot and CFD-POST, they show the different features near the boundary region of rotating domain.
The high value appears in the results calculated by Tecplot, but the low value occurs in the results by CFD-POST. Why the results are not the same? They are used the same vortex method! The method could be selected in each software because it is built-in functionality.
Someone know about it? Thank you!