What makes something a client script? Is it when they are in a player, is it when it is a LocalScript, or is it something else?
ServerScript(s): ServerScripts run on the virtualized cloud servers at ROBLOX HQ. They have access to "almost" anything that interacts with the server environment. They also cannot access certain things that are exclusive to the Client.
ClientScript(s): ClientScripts run ON YOUR PC/Mac and do not associate themselves with the ROBLOX servers. Using the defined environment provided by the ROBLOX Client, LocalScripts can perform actions locally on your machine.