HCl is a strong acid while NaCl is a salt. Since NaCl is a salt, once it dissociates or undergoes electrolysis, the individual ions Na+ and Cl- will conduct electricity. Pure HCl doesn't dissociate; therefore, it will not conduct electricity. However, less pure HCl will conduct electricity since it still dissociates. Both HCl and NaCl are soluble in water. HCl is volatile while NaCl is non-volatile.
