LeadSled, sorry I missed your reply for three months; I need to maintain my 0.03 posts per day batting average.
Answer: A private flight with your mates is a private flight where you can pretty much decide what to do and terrify them in the process. A commercial operation is a hire and reward service provided to people you do not know who are paying you to represent the AOC holder and provide a flight within your personal limits, the aircraft's limits and the environmental limits, ie. a far higher standard is required.
That may be a piece of piss to you and I, however at some point we were both "the pilot who may very well be in his/her first commercial flying job", ie., at a transition point where a guiding hand is required.