Thanks for the explanation. I've tried both on my mandolin lately (it's acoustic, no EQ). To me the string gauge makes more difference, but I think the tone of the phosphor-bronze suits my mandolin better.
I'm jealous of guitar-players, who can walk into a music store and have a wide choice of strings right on hand. The stores near me seem to think that mandolin players all want the same two gauges of one brand of strings.
I was used to using medium gauge guitar strings,, but then I bought a Simon & Patrick guitar with a cedar top and cherrywood body. The medium strings didn't sound as good as the ones that came on it, so I checked the company website, and they recommended light strings. What a difference in tone! So I guess it depends to some degree on the particular guitar which strings sound best.