To me pod sounds like a recording of an amp, even if played through an amp.
This also means that actually in a recording context and a complex, readily produced song you won't hear much a difference.
But I think it's more the "feel" of an amp which is missing with pods and the like, how it's spongy or pushing back and how the same chord played twice sounds different each time you hit it, because of the complexity of the analog circuits.
Actually I like playing the modeler sometimes, I think I am much quicker and smoother in my playing with the Tonelab, but the battle and effort is lacking a bit, which results in less attitude coming out of the speakers, if you know what I mean?