I am paraphrasing from the super collider book, from chapter 4 by Stefan Kersten, Marite A. J. Baalman, and Till Bovermann:
User Datagram Protocol aka UDP sends individual packets of limited size with no guarantees of delivery, it also has lower overhead than TCP. (overhead: is any combination of excess or indirect computation time, memory, bandwidth, or other resources that are required to attain a particular goal, http://en.wikipedia.org/wiki/Overhead)
Transmission Control Protocol (TCP) exchanges a continuos stream of binary data between two connected hosts.
Open Sound Control (OSC) like UDP is message based (rather than connection oriented ie TCP). Streams of messages are packaged by prepending a 32 bit byte count to each message packet before sending.
OSC packets come in two types: messages and bundles. Messages are individual commands, /formatted/like/this. Bundles are collections of messages paired with a 64 bit time tag. Messages in the same bundles are guaranteed to be executed atomically by the receiving host. Messages in bundles are executed at the same logical time or not at all.
I thought this was useful info and a great presentation by the chapter authors! Enjoy!!