Low and High Protein Content in Hard and Soft Wheat Flour

Hello all. I have an issue which I hope the professional bakers here will care to answer. In my country, flour millers produce more than one brand or variant of hard and soft wheat flour. The practice is for them to sell in the market 2-3 brands or variants, both for soft and hard wheat flour.

For hard wheat flour, I have observed several differences in the 2-3 kinds that they sell, but the thing that interest me most is the protein content. As far as I can tell, the higher the protein content of the flour, the higher the price becomes.

I have also asked friends who have experience in baking and according to them, aside from the price, another trait of the higher protein content hard wheat flour is that it absorbs more water and in effect produces more per pound. This, I suppose, is subject to debate.

Aside from the price and possible increased water absorption, what are the other possible differences and advantages over the other between high and low protein content hard wheat flour?

If any, are these differences and advantages in high and low protein content in hard wheat flour applicable in soft wheat flour?

Thanks.