Why is it so easy to tell the difference between live and recorded music?

AR chose small ensembles or solo instruments for their tests.  A symphony orchestra would be a far more challenging.

I don't think it's always easy to tell the difference since there have been specific occasions where I've been fooled, but in general, live sound reacts with background noises in a different manner than amplified music.  It floats above it as opposed to cutting through it.  Sorry for the obscure language.

I would have to say that audio gear is so good at this point that I am 99% happy with recordings sitting on my comfortable chair in my living room which has decent (although not perfect) acoustics.
I have difficulty EVER recalling hearing great sound at a live concert, although the experience alone was well worth the trouble of going in the 1st place.  When s great performer comes out on stage, whether it's Frank Zappa or the LSO, i get goosebumps anyway.  But for truly balanced sound and no coughing or other distractions, i can now die a happy person. Only ballet or opera, (or Woodstock) requires a ticket and a good seat (imho).  If you can get a string quartet to come over to your house and play, that (of course) would be terrific also...

...."Live v. Not...."

Dynamics, yes...but as an 'omni fan'....Ambiance....MHO, obviously...

...as soon as you move....(Generally*....)....*poof*...

( * = ...unless you've been very careful and/or very lucky to have the 'disposable income' to 'attend to the details'....in whatever manner or fashion you felt compelled to....Again, IMHO....)

I totally agree with everything Trelja notes particularly tone/ timbre, it's always been and continues to be so obvious to me. I find it remarkable how good recorded can get considering all the challenges posed. To me what is most important is conveying the emotion in the performance.

My wife and I attended a middle-school grandchild's band concert last night. Dynamics/tone/timbre. Especially dynamics. Amazing really. Reminded me how inadequate my system is in comparison. Reality check. Sigh...

Tom