PBE per type of aircraft
 

Hi everyone,
I am currently working on a study project and I hope you will be able to help me to understand some points about airline safety equipment.
It seems that different airlines have different quantity of cabin crew positions per type of aircraft.
Does it mean that there is different quantity of PBE in the same type of aircraft in different airlines?
What kind of documents regulate the number and model of PBE for a particular aircraft, except international standards like SAE, etc? Are there likely to be internal airline standards about that?