The R in IFR/VFR stands for Rules, but I don't think it's intended the way you're trying to use it here. It's not a rule as in a regulation, but a rule as in a definition of the procedures. For example, speed limits are a regulatory rule, but the area rule for wing design means the technique or method for producing a design within provided limitations.
Flying under Instrument Flight Rules means the flight is procedurally conducted by reference to instruments. That's it. In order to operate a flight under IFR, most parts of the world have implemented regulations that govern who, when, and how this may be done. In the USA, that includes being in constant 2-way radio communication with ATC, for obvious reasons. One of the Rules about IFR operations is that ATC will make it the highest priority to provide separation services to aircraft operating under IFR, but the pilot is still ultimately responsible to see and avoid other aircraft, whether they are operating under IFR or VFR.
Flying under Visual Flight Rules means the flight is conducted primarily by visual reference to the ground. In Class G airspace, the minimum flight visibility is 1 Statute Mile, and the requirement is just to remain clear of clouds. Most people would not consider those to be prevailing Visual Meteorological Conditions, and that probably falls under the "legal but stupid" category of minimum regulations. Other airspace classifications have different requirements for flight visibility and distance from clouds in order to operate under VFR. Failure to adhere to any of them, or to the equipment, certification, communication, or other requirements defined in the regulation, is a violation of those rules -- but not a violation of Visual Flight Rules.
Position and hold