Better engineered sprayer jets, adding better sensors to determine water turbidity and other water metrics, additional sprayer arms (second-rack sprayer arms were pretty rare IME in the 90s, common today), automatic soap dispenser systems dispensing just the right amount of soap or rinse aid given on various water properties, etc.

Even today a super basic mechanical timer based washing machine probably won't work as well or as efficiently as a high end unit with various sensors and logic.

There have been improvements in the amount of water used since mine was made.

Water consumption I can imagine, but power consumption? And by how much anyway?

Improvements in these appliances always feel a little like those percentages on dishwashing liquid. If I would multiple all the improvements since 1990 I think one drop of detergent will be enough for the rest of my life.

I recon decreased energy consumption would be achieved by decreased water consumption, since less water needs heating.