All Mk2 Fiat Ulysees were equiped with 6 airbags as standard (driver, passenger, 2×seats and 2×side curtain). What are the actual differences in airbags and airbag ECUs?

Airbags for exaple look exactly the same, use same connector but have different catalog numbers written on them - that is for the airbag used on same place (right side curtain for instance), but different year of production. Are they interchangable even if they do not have same catalog numbers? If not, why not? What is different?

Same question goes for airbag ECUs. Are they interchangable?
Again same connector, same outside looks etc
EPER only says "new airbag control unit."

Side impact/crash sensors seem to be fitted as standard too. Where are they located?