I don’t have numbers for you, but I can say that both reduce the output if compared to a light with a reflector. I am sue there are numbers out there comparing lights in the same situation or theorizing about that.
I did some close up tests a while ago using different kinds of TIR optics. Essays with TIR lenses on Convoy S2+: XML2 + XPL-HI [Update] - #15 by MascaratumB
I will try to find my frosted optic an take some photos to show you how different they can be in terms of beam.