There are variations in medium-/high-voltage surge-arrestor designs. Materials are silicon carbide and zinc oxide. There are gapped surge arrestors, most often but not exclusively associated with the silicon carbide medium. Also, there are gapless versions, typically offered with zinc-oxide devices. These solid materials and spark gaps are all considered to be non-linear resistances in practical application.
For power-systems overvoltage protection, silicon carbide generally has a longer history than zinc oxide but with some limitations, else newer zinc oxide would have little acceptance.
Understand that manufacturers’ literature will have inherent bias, while consensus standards are more general in their assertions. Another important difference is that product information is available just for asking, whereas consensus standards most often require payment to obtain. In ANSI regions, IEEE “C62” surge-protection standards prevail. One list is standards.ieee.org/catalog/olis/surge.html