18 LED's may seem excessive, but by using so many tiny, but bright, LED's the light output is spread evenly, rather than several pools of light from fewer, but larger ones.
The LED's are effectively mounted on a small printed circuit board, which also includes a protective voltage regulator. The bulb can be angled slightly to concentrate the light output a little by rotating the bulb, and I have done this so that it illuminates my Sony head unit a bit more to help fit the removable panel (fiddly) in the dark.
I've not seen the Halfords one, so can't compare I'm afraid.
ceejbee.