info_command_server is the counterpart to info_command for commands which need to be run on the server. In single-player the distinction does not need to be made as the client and the server share a console. This entity is needed to ensure co-op compatibility for your map. Read the info_command entry for details of when to use each entity.
Please note that features such as ONLY_ACTIVATOR and RESEND_ON_LOAD are not offered for info_command_server, since these spawnflags are for targeting individual players, but commands to the server will always apply globally.