Are gold and silver coins the same weight?

Could you clarify for me, are gold and silver coins typically of identical weight? I understand that both are precious metals and have been used as currency throughout history, but I'm curious if there's a standardized weight for each type of coin or if they can vary significantly in terms of their mass. I'm interested in learning more about the differences in weight, if any, between gold and silver coins and how that might impact their value and use as a form of currency.