What is the difference between 2 core and 3 core cable?

2 core cable does not include an earthing wire and can be used with any electrical item with an outer surface which is predominately made from a non conductive material such as glass, plastic, ceramic or bakelite.
3 core cable can be used for these types of fittings also, however a 3 core cable MUST be used with any light, lamp, bulb holder or fitting with a conductive or metal exterior surface to ensure against risk of electrocution or serious injury.
We recommend that any fitting or installation is done by a qualified electrician, do not risk installation yourself if you are at all unsure.