Watts is Watts -- and a 1500 watt heater, no matter what it is made of, gives you about 5100 BTU. You will find resistance heaters, oil heaters, ceramic heaters, carbon heaters, infra-red heaters, quartz heaters, and quartz infrared heaters -- all kinds of heaters, almost all of them rated at 1500 watts. Every one of those 1500 watt heaters puts out 5100 BTU in an hour. No exceptions.
For making heat, none is better or worse than any other. And regardless of claims, none is more efficient at making heat than any other. The thing that makes people like infrared heaters is the way they radiate heat better and farther than the typical resistance heaters with a fan.
On the other hand, since this heater has a fan and only a 10" x 2.5" (est.) opening for radiated heat, this is as much a fan heater as an infrared heater.
That said, there are some confusing statements about the output of this heater. It has only one heat setting, but it has dual heat (power) levels (750 and 1500 Watts), but there's no control switch for the heat level, but the thermostat switch puts the heater on the higher heat level when set above 77 degrees, and for larger rooms you need the higher power level, so you had better also want 77 degrees.
It's hard to figure why lifeSMART wants to tie themselves in knots trying to explain the lack of a proper heat level (power) switch; but Marketing people are like that -- high on techno-babble and low on tech. No matter, it can put out its full capacity if you turn up the thermostat, same as all the rest.
For what it's worth, I buy 1500 Watt, fan-forced resistance heaters for the lowest price available. After all, Watts is Watts.