pir plasterboard insulated vs normal insulated

[ELplastering123]

Alright lads

Spec is to use pir 38mm insulated board which is proper expensive whats the difference between this and normal insulated board ?

 

[owls]

gives a beter u value

 

[plasterjfe]

I would have thought most if not all insulated plasterboard is pir, pur, phenolic. There can't be much different in the price they are very similar things. Polyurethane resins