Next Generation Biometric Passports

Not being political but the Lib Dems say they would save £400m by scrapping these.
Does anyone know how these passports differ from the current biometric ones and what the consequences of scrapping them would mean in practice?
Are we tied into implementing them as part of an international agreement? Would not having them mean having to undergo additional screening / questioning at immigration?
Am not sure how the £ would be saved as surely the costs would be passed onto us when we renew
Does anyone know how these passports differ from the current biometric ones and what the consequences of scrapping them would mean in practice?
Are we tied into implementing them as part of an international agreement? Would not having them mean having to undergo additional screening / questioning at immigration?
Am not sure how the £ would be saved as surely the costs would be passed onto us when we renew