Why do some oil heaters (“red diesel”) use also electricity and some not

I would like to install a small heater, for heating one room, that runs on heating oil, i.e. "red diesel".

After a brief look on what is available for sale, I noticed some of them require also an electrical connection, and use from 10W to 50W of electricity, and some others don't require any electricity.

For example the Webasto AirTop2000 diesel heater uses 14 to 29 W: http://www.webasto-outdoors.com/service/faq-knowledge-database.html#c163

Also the wikipedia article on "Heating oil" says:

For efficient burning, the oil is drawn from the tank into a pump and
pressurized (residential) to 1,034 kPa (150 psi) and forced through a
filtered (specific to appliance) nozzle, into an atomized spray
pattern. It is then ignited through the use of a step-up transformer,
taking 120 or 240 V AC and stepping it up to 10,000 V AC.

which implies that generally oil-heaters use electricity, but then I see many oil heaters of this kind:

This does not have any electricity connection at all, so I am a bit confused. Can someone explain me what is the difference, and are there any significant benefits on using the types which use electricity?

In my application the only electricity that comes is also from a diesel generator, so I would like to avoid having the heater use any electricity, unless there is any significant benefit, like better efficiency which offsets the diesel used for generating the electricity it uses.

Also, what type of oil heaters can you recommend?
I would like to be able to burn different types of oil in it too, like diesel fuel from the petrol station, rapeseed cooking oil, kerosene, used engine oil, just anything similar – are there heaters which will burn all of that?