My supermarket sells two heating-fans that look similar, but one of them costs twice as much as the other. The only difference I noticed is that the more expensive one says it has a "ceramic heating body". What advantage, if any, does such a heater have? (I need it for heating a home in a standard apartment).
According to the Wiki post regarding ceramic heaters, the heating element in this type of device has a positive temperature coefficient (PTC). This means that as the device gets hotter, the power it accepts is reduced, making this a self-regulating heater.
Resistance heaters using nichrome wire or other high-resistance wire are also PTC but according to the same post, the level of temperature required is much higher.
The ceramic heater would have a greater perceived level of safety, although most of these devices have safety features for tip-over protection.
It's possible (but not researched) that ceramic heaters have a higher production cost. It's also possible that these heaters enjoy a perceived high-tech aspect, as resistance (hot-wire) heaters have been around for decades.
There may be advantages/disadvantages in terms of safety, though all electric space heaters have to meet certain safety guidelines, and all are potentially dangerous if used near children & pets (burns), draperies & furniture (fires) and water (shocks).
From an efficiency standpoint, while some types of electric heaters may seem to produce hot air better, that is more likely due to quality & speed of the fan (for those that have fans) than anything else. Every electric heater is fundamentally limited to the simple equation of 1 kWh = 3,412 BTU. Unlike lighting and other uses where a more efficient device means "less heat", except for the fan (which uses very little power compared to the heating element), all the power used in a space heater should be turned into heat. If it is "wasted", it just becomes heat in a different place (e.g., wires become hot) and the end result is the same 3,412 BTU/kWh.
Most portable heaters are sized based on the available circuit size. In the US, that means 15A. Plenty of people have 20A circuits, particularly in newer homes, but very often the receptacles are designed for 15A loads (NEMA 5-15 instead of NEMA 5-20), so that is the effective limit - most manufacturers don't bother to make a bigger heater because it would result in too many returns for "what kind of crazy stuff are they selling that won't fit my outlet!". Plus, if your heater was designed for 20A then if you put any other significant load (even a few hundred Watts like a computer or food processor or whatever) on the same circuit then you'd be tripping breakers regularly. So 15A is the default. That means a maximum of 15 x 125 = 1,875 Watts (which is why you will see 1,875 as the limit on a lot of timers and other devices). But continuous loads (and a space heater in a room that starts out cold is most definitely a continuous load) are limited to 80% = 1,500 Watts. Therefore you see the vast majority of portable space heaters in the US rated at 1,500 Watts. And 1,500 Watts of heat is 1,500 Watts of heat, no matter how good the fan is or how fancy the cover is or what new type of heating element is used. A good fan will certainly help disperse the heat, but in the end, 1,500 Watts can only do so much. A furnace for a typical house might be 50,000 BTU or more. There is only so much that 5,100 BTU can do.
The basic difference will be the life of the elements. The ceramic body support for the element reduces stress on the element so they fail less often. I find the thermostats fail in small portable units more often than the elements so for a small unit I would not spend the extra. If this is a built in I would spend the extra for a ceramic body but since you said supermarket I would guess it is a portable and I would go with the one at 1/2 the price.