There are some important technical differences that result in significantly different approach.
Usually chatrooms are hosted on "own servers", meaning the same servers where associated site is. That means the admin next door to the moderator has a complete power over the user list, user registration, blacklists, access to detailed IP data of connected users, features of the chatroom, registration requirements, etc, etc. Moderators act on own turf, can request features or different help from the system side - generally, act on home ground.
IRC usually means big global networks, multiple servers spanning many continents, a crew running them in no way associated with channel operators (you) and responding to your requests when they feel like responding. Your channel is your responsibility, but first you must fit your own policies into 3rd party policy, you can't count on quick reaction to users who, say, took over the channel, you usually live in neighbourhood of several thousand other channels (and their users a click away from joining), and with most connection data hidden.
The set of problems and solutions is entirely different.