Recorded vs. Live Performance
Two distinguished thespians opine on the differences between taped and live performances.
In a TV interview, the distinguished movie actor, Gene Hackman, stated that when acting in films, he often found himself withdrawing, being more introspective, and minimizing his physical gestures, things he had seen many other stage actors do when making the transition from working in the theatre, where one has to be concerned about "hitting the back wall*," to acting in motion pictures, where many of those same gestures would probably appear unnatural or seriously exaggerated when viewed through the intimacy of a camera’s lens.
In a similar statement, the great thespian, Sir Lawrence Olivier, once opined that acting on the stage is about acting, whereas acting in films is simply about "being" (in front of cameras). Others have posited that there are even further adjustments needed when acting for the small screen (TV) as compared with the large screen (theatrical motion pictures) since every sound and gesture appears even more exaggerated. (Theatrical motion pictures are technically adjusted for TV transmissions, according to an industry source, but this writer is clueless as to how this might affect any of these issues.)
From the musician’s perspective, with the advent of the Digital Age, we have again reached a point, as in earlier times in our developmental history, where live and recorded performances can often require different technical disciplines to accomplish the same musical results or effects. This is due to the increased sensitivity of today's recording devices, how (technically) the music** is recorded, and the various ways the final recorded product is disseminated. Musical and technical issues like dynamics, musical nuances, and general balances are often approached in a way not dissimilar to the experiences and observations of the two actors mentioned above. For musicians, this is exactly the opposite of the way things were a half-century ago when the rule-of-thumb was to exaggerate/overdo many of those same elements to get the desired recorded effects, for quite different reasons: a lack of sensitivity of recording devices and/or the record fabrication/reproduction process. Consequently, because of these differences, what might work well today in the concert hall may not be as successful on tape, and vice-versa, just as it was a half century ago, but quite obviously for different reasons. This could possibly explain why some performers are, and were, more convincing in one or the other of these venues. It is also one (of many) of the reasons some modern day recording artists prefer to "sync" their performances to their own recordings rather than performing "live.
* Hackman's words used verbatim here, but they are a part of the common lexicon of actors/musicians relating to the projection of sounds and gestures to the back of a theater or concert hall.
** "I have a quiet voice and sing 'in' rather than 'out', working the mic (microphone) to shape the vocal."-singer Boz Scaggs in the liner notes of one of his recent CDs.