[cups.general] What's the difference in printers.conf between socket:nnn.nnn.nnn.nnn and ipp:nnn.nnn.nnn

[Gerald Britton]

I noticed that most of my printer definitions have a URI of the form:

    socket:nnn.nnn.nnn.nnn

I also see that I can set it to:

    ipp:nnn.nnn.nnn.nnn

I'd like to know what the difference is in how CUPS processes one vs.
the other and if there is a compelling reason to prefer one method.