From a Canadian Military perspective:
DUMMY AMMUNITION - Inert ammunition items that are representative of operational or practice items in that they conform generally in size, shape and weight. They do not contain explosives. They may be empty or be filled with inert material and may be constructed of materials different from those of the items they represent. Dummy ammunition is used for instruction and for training in assembly and disassembly, handling, loading and unloading weapons, cycling weapon feed systems, throwing grenades, mine laying, preparing demolition charges, placing booby traps, and other similar drills. It is not designed for projection by an explosive charge or by mechanical means. Dummy ammunition is coloured bronze and is marked conspicuously in two places with the word "DUMMY" in black. Where it is not practicable to apply body colour or other means of positive identification, dummy items may have holes drilled or fluting placed in the areas normally containing explosives. When space permits, these items are also metal stamped or stencilled "DUMMY" in black or white lettering as appropriate for the particular background. Dummy ammunition was formerly classified as drill ammunition.
DISPLAY AMMUNITION - Inert ammunition items that are representative of operational or practice items in that they conform in size, shape and appearance, and are colour coded and marked to simulate their operational or practice counterparts. They do not contain explosives. They may be full section, cut-away or sectioned to expose internal arrangements of component parts. Display ammunition is used for instruction purposes and for display, eg, in museums. It is never used for drill. Display ammunition is marked conspicuously in black or white with the word INERT. This marking is generally at right angles to the other markings. Where appropriate, the word INERT may be metal stamped in lieu of being stencilled.
The cartridge shown on the link you provided would be considered Display Ammunition since it has colour coding on the projectile. The military generally has a large quantity of Dummy Ammunition so soldiers can practice various skills such as loading there rifle magazines, laying mines, etc. They generally have a very limited number of Display Ammunition which are held at training facilities and some units for refresher training. Often Display Ammunition costs much more than the live item. When I was in the infantry we had several hundred Dummy 5.56mm cartridges to practice loading magazines, machine gun drills, etc, but we only had one or two Display cartridges representing ball, tracers, armour piercing, etc which they used to test us on colour recognition.
