Not sure of the efficiency of either.
The red flame radiant heater does just that, radiates heat in front of it.
I have a blue flame in my shop. Would be the size of a 5 brick radiant heater.
The heat from it doesn't radiate at all, just rises. My shop is 30x48 and open. Itrarely gets below 40 any time, but when I use the heater I set a 6-8" diameter fan to blow across the top of the heater. When I do this I have to turn it down in 30-45 minutes because the shop gets too warm.
Needless to say, I like the blue flame.