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.
In SF4 (trigonal bipyramidal), there are three equal equitorial bonds (with one lone pair and two F atoms) and two axial bonds (with 2 F atoms)
the axial bonds are longer due to more inter atomic repulsions between the F atoms.
therefore all the bonds in SF4 are not equal (axial>eqitorial)