Ruby Wallace

There are differences between the two models, especially the near-wall treatment. k-Omega SST is a y+ insensitive model. This means depending on the local refinement near the wall, it would either resolve the viscous sub-layer or use a wall function. You can refer in drift boss

Non-equilibrium wall functions are recommended for use in complex flows involving separation, reattachment, and impingement where the mean flow and turbulence are subjected to severe pressure gradients and change rapidly.

Enhanced Wall Functions (as a part of EWT) User-Defined Wall Functions are also available depending on the choice of turbulent model