Both efficiency and durability of the hubs can depend on quite a few things. Among them being the materials used, which includes their hardness and specific alloy. Steel is by definition an alloy. Unlike aluminum which is a basic element. So why do we call aluminum alloy? Well probably because for most usage aluminum is alloyed with other things to make it more durable. As is iron to create steel.

We could go deeper into that. But suffice to say that the exact type steel or aluminum used in the hub and bearings construction will make a difference. As will how well the overall design is optimized for efficiency and durability. And for how well the components are machined or made. And for how well quality control is maintained.

The type of bearings being the best for efficiency won't matter if the manufacturing of them was crappy.