Difference between same value ceramic capacitors from different manufacturers
When are these differences important? 


It depends what you're trying to do.

If you want low leakage, then the difference between 111Mohm and 21Mohm is very significant, but irrelevant for supply decoupling.

If you were building a sample and hold, the then difference between 5% and 15% DF would be large, but you wouldn't want to use something as bad as 5% anyway. It's no coincidence that the higher dielectric constant has the higher DF.

A vital spec both caps are missing is the voltage coefficient. You will only get 4.7uF at 0v. Depending on the case size (oh yes, even within one manufacturer, as the case size changes the voltco changes) you may lose over half that capacitance at the rated voltage.