Every IRCd is different in some way and feature levels vary to a great degree too. You need to read documentation that comes with each one you look at to confirm existance of a particular function.
Originally IRCds were unique to each network. They were usually written by the people that ran them. Apart from a few networks which still maintain their own coding teams it doesn't work that way anymore. People use either commercial software taylored to their portals or they make use of IRCds written for other networks and then usually use a webchat aplication written by another company/individual if they want that added too.
