Materials? Design? Maintenance?
To be honest the subtle changes between designs are going to be way beyond anything that's worth discussing here, even if Rolls were willing to divulge what is ultimately commercially sensitive information.
Yes there are many accounts of the brick walls on flight decks being damaged. It was a common problem back in the 70's. For this reason the brick walls were later replaced with reinforced concrete.
Thank goodness for the advent of kevlar-concrete composite technologies. It's what gives Boeing's their distinctive brown instrument panel don't you know.