Difference between boiler mountings and accessories?

Boiler mountings are different fittings and devices which are necessary for the operation and safety of a boiler .e.g. pressure gauge, safety valves , steam stop valve etc Normally these device are mounted over boiler shell .Boiler Accessories are auxilary plants or parts required for steam boilers for their proper operation and to increase efficiency of the boiler .e.g.feed pumps, super heater , economiser etc