All the bonds in SF4 are not equivalent. Why ?
Of sulfur's total of six valence electrons, two form a lone pair. The structure of SF4 can therefore be anticipated using the principles of VSEPR theory: it is a see-saw shape, with S at the center. One of the three equatorial positions is occupied by a nonbonding lone pair of electrons. Consequently, the molecule has two distinct types of F ligands, two axial and two equatorial.
Axial Bonds suffer more repulsion than equatorial bonds as they are reppled by both bonding and non bonding electrons...hence the bonds are not equivalent.