Isostructural species have the same shape and hybridization. The central atom in $\text{SiCl}_4$ is silicon, which has 4 valence electrons and forms 4 sigma bonds, undergoing $sp^3$ hybridization with zero lone pairs, resulting in a tetrahedral geometry. Similarly, $\text{SO}_4^{2-}$, $\text{PO}_4^{3-}$, and $\text{NH}_4^+$ all have a central atom with $sp^3$ hybridization and zero lone pairs, giving them a tetrahedral shape. However, in $\text{SCl}_4$, the central sulphur atom has 6 valence electrons, forms 4 sigma bonds, and has 1 lone pair. This results in $sp^3d$ hybridization and a see-saw shape. Therefore, $\text{SCl}_4$ is not isostructural with $\text{SiCl}_4$.