The former are limited to the server(s) they have specific access to; however, global operators can perform actions affecting all users on the network.
A user can become an operator by sending the command /oper to the irc server they currently are on using a pre-selected username and a password as parameters.
The command only works for the server which has the proper O-line in its IRCd configuration file.
These ranks often depend upon the IRCd software used, though a few specific access levels remain fairly constant throughout variations: The Local operator (LocOp) is the lowest in operator access levels.
GlobOps may perform G-lines or AKills (network-wide bans) and shun (forcibly mute) users over an entire network.