are pex a and pex b fittings the same?
Flexibility - PEX-A is the most flexible, allowing for it to be fastened by cold expansion, which allows the end to be fluted prior to inserting the fitting. PEX B is not expandable and you should never expand the end of a PEX-B pipe. Kink-Resistance - PEX-A has the greatest resistance, PEX-B the lowest.