In my opinion, TI does not really "differ" in swimming itself, because the goal of TI is to teach everyone to swim well. "Swimming well" is available to everyone and is reached by dozens of non-TI coachs and easily seen in major swimming events.
The importance of TI, as I see it, is the philosophy through its set of principles and their application how to train to be the best swimmer you can be. By breaking swimming down in the component parts of elimination and propulsion, with elimination the more important Terry proceeds to provide the principles that make elimination effective including relaxation, balance, long-bodies, and core body movement. All four competitive strokes are taught with this philosophy.
So TI backstroke teaches how to balance while on your side, how to time the arms to have a patient catch, and how to engage the core muscles with a connected shoulder movement attached to core muscle rotation.
The Backstroke video can be found here: http://www.totalimmersion.net/store/...every-body.htm
l, and the book for all four strokes is here: http://www.totalimmersion.net/store/...-imagined.html