It has the firing tip at one end and the other end is recessed up into the metal casing (the thread part) of the plug.
This system seems more logical to me, but I’m sure NGK have their reasons for their choice!
For further details, have a look at this Bosch spark plug reference chart.
The spark plug heat range does NOT control the temperature at which the engine runs; fitting a ‘cold’ plug will not make an overheating engine run colder, nor will fitting a ‘hot’ plug make a cool-running engine run warmer.
Engine temperature is governed by factors such as the timing and fuel-air mixture settings, running conditions, lubrication quality, compression and cooling system design to name a few, but certainly NOT by the spark plugs heat range.
The Champion system is similar to that of Bosch in that the smaller the number, the colder the plug (4 is the coldest) and the bigger the number, the hotter the plug (19 is the hottest).
Other manufacturers may have completely different labelling systems again, so it can get very confusing!
You therefore cannot easily directly compare the heat ranges between different brands. With NGK spark plugs, the number in the middle of the part code designates the heat range so a “B7ES” has a heat range of 7 and a “BP9ES” a heat range of 9.
A smaller number means a hotter plug (2 is the hottest) and conversely a higher number means a cooler plug (12 is the coolest).
Overheating of the spark plug may also cause the electrodes to wear away and the ceramic insulator nose to bubble and breakdown.