Resistance and capacitance (of parallel plate capacitors) both have two formulas for them: $R=V/I$ and $R=ρL/A$ for resistance, and $C=Q/V$ and $C=ƐA/d$ for capacitance. For any given resistor and capacitor with given dimensions, there is only one possible value of resistance or capacitance calculated using the second formulas (formulas with variables of dimensions of the component). However, depending on the potential difference across the components and many other variables (e.g., current for resistance and charge on the plates for capacitance), it seems like a given component can have many resistance or capacitance values different from the value given by the formulas considering the dimensions of the component.
So, my question is: What is the difference between the two formulas for each of resistance and capacitance? Under what circumstances is one formula more applicable than the other?