Whats the difference between these two seats?

[pujaro]

I have bought a front passenger and driver seat for bmw e60. The driver seat has these "boxes" under the seat (yellow and silver, they looks like a battery, but i know the are not) but the passenger seat doesnt. My question is what are these "boxes" do and is it normal that i didn't get one under the passenger seat?





https://ibb.co/tP4C4tW (driver seat)
https://ibb.co/DWgsQM5 (passenger seat)