The key difference between thiocyanate and isothiocyanate is that thiocyanate is a functional group in which the alkyl or aryl group is attached through the sulfur atom whereas isothiocyanate is the linkage isomer of thiocyanate in which the alkyl or aryl group is attached through the nitrogen atom.
Thiocyanate and isothiocyanate are functional groups containing carbon, nitrogen, and sulfur atoms. These functional groups have the same connectivity of atoms. That is, the carbon atom is in the middle, while nitrogen and sulfur atoms are attached to its sides. However, the chemical bonding between these atoms is different from each other.
