That is a lot of heat, so the choice of which model to purchase becomes critical to long term mental stability. Both types use a circular wick to transport fuel from the tank to the burner unit, sometimes called a catalytic converter. That burner unit is the heart of the heater. In a radiant heater the burner unit is encased in a glass cylinder, with a half circle of reflective metal behind it. Radiants do produce some convective heat, but that is ancillary to their primary design.
Convective heaters heat the air, which then heats the environment.
The burner unit is encased in a steel sleeve, not glass. Convective heaters are generally rated at 20,000 BTUs or more and radiate heat in all directions. They need at least three feet of clearance all around from combustible materials, or your home could become uncomfortably hot. The reason for knowing the differences between radiant and convective units is because of the effect on the burner units. The very act of radiating heat robs the burner of heat during start-up, so a radiant heater may take up to 6 minutes to warm up to operating temperatures, whereas convective heaters can be at full operating temperatures in as little as three minutes.