PAR is a subset of lumens, the fraction of the available light (luminosity) that is useable by plants (e.g., that falls within the favorable spectrum). In that respect, it has very much to do with growing plants.

If you have a light that generates 100% PAR light, is that better than a light that only generates 30% PAR? If lumens had nothing to do with growing plants, then the answer to that would always be 'yes'. But the real answer to that depends...on the respective lumen outputs of the two lights being compared.