What type of light is a 20 watt energy saving bulb Halogen Incandescent neon or fluorescent?

A 20 watt incandesent bulb is dim. For a medium sized room you need 100 watts.

A 20 watt halogen bulb is brighter but still quite dim. These are marketed as low-energy but they are not. For a medium sized room you need 80 watts.

A 20 watt fluorescent bulb can light a medium sized room quite brightly. This is a genuine low energy bulb.