OpenCanvas has a chat function, but it uses the host's computer as the server and does not support multiple channels at once. As a client, I'm not even sure it allows connecting to multiple servers simultaneously. I'm pretty sure it allows chat logging (as it of course allows for logging of the images produced) but it lacks several useful features like message highlighting and DCC filesharing tools. Then again, OC's focus is really on allowing multiple users share a canvas and draw simultaneously. The chat feature is really just a useful add-on to aid in communication between participants in a single session.
Internet Relay Chat, on the other hand, is only a protocol and not a specific program. Supplying mIRC as the canonical IRC client, the first difference of note is the fact that unlike OC, mIRC does not have any sort of drawing tools or even a shared canvas area. In fact, there are no drawing tools present because mIRC is an internet chat program, and nothing else.
Bringing /prog/ back to its people
All work and no play makes Jack a dull boy
All work and no play makes Jack a dull boy
All work and no play makes Jack a dull boy
All work and no play makes Jack a dull boy
All work and no play makes Jack a dull boy
All work and no play makes Jack a dull boy
All work and no play makes Jack a dull boy
All work and no play makes Jack a dull boy
All work and no play makes Jack a dull boy
All work and no play makes Jack a dull boy
All work and no play makes Jack a dull boy
All work and no play makes Jack a dull boy
All work and no play makes Jack a dull boy
All work and no play makes Jack a dull boy