The difference looks to be the choice between lectures (TSFX) or small-group workshops (HSC in the Holidays). I am going to HSC in the Holidays as I would rather have the chance to ask questions, have worked marked by actual markers and practice a range of questions. Also, all my subjects are covered at Macquarie/UTS so this is easier.
Some of my friends went to this last year and they said it was excellent.