Lets imagine this example-
Captnhook is recording an Americana band from a position is out in the center of the audience, and decides to try a 3 channel multi-microphone recording arrangement, lets say a small Decca tree consisting of three omnis arranged in a broad triangle. The good Capt'n was able to achieve the wide 48" left-right microphone-position spacing he wanted, but due to the limitations of his mic-bar he was unable to space the center microphone forward of the other two microphones by the 24" he was hoping to achieve, so instead, he has all three microphones are arranged along a line. "No problem", he thinks to himself, "I'll just delay the L/R pair to effectively shift them backwards in time with respect to the center mic channel, that will achieve the same thing as physically spacing them".
A rowdy audience excitedly files in. They know all the songs and have brought their own noise makers along to join in with the revelry. The accordion player takes the stage, nods at the good Capt'n and rips into the first number. Sure enough, almost immediately there is a young man furiously playing polyrhythms on a triangle off to the left of the recording position, a woman banging on a small tambourine to the right, and two guys tooting a penny whistles directly behind. Fortunately everyone is in tune and in the groove. What could have been a nightmare audience for a good recording turns into a beautiful and engaging live-performance experience. Everyone heads home smiling.
Capt'n gets home, transfers the files and gets to work.. To simulate the center microphone being positioned forward of the Left/Right by 24", he applies a delay of 2ms to the Left and Right mic channels, since it takes about 2ms for a wavefront to travel 24". He zooms in and looks at the waveforms to find the first crack of the snare. The wavefront from the drummer hitting the snare pings the center mic channel about 2 milliseconds prior to the Left and Right mic channels. Great, it works!
But what about the other sources of sound? The wavefront from the polyrhythmic triangle player off to the left would normally ping the left mic 2ms before the center mic, and 4ms before the right mic (First left, then center, then right, with 2ms between each arrival). But instead it pings both left and center channels simultaneously, and doesn't ping the right channel until 4ms later. Hmm. For the penny-whistle players its even worse. The sound from the penny-whistle players in back should arrive at the Left/Right channels 2ms before it arrives at the center channel out front, but instead it does the exact opposite- arriving at the center channel 2ms ahead of the Left/Right channels.. as if the two penny-whistle players and all the audience with them in back were actually standing out in front of the recording position, rather than behind it.
Most definitely not the same! Similar time-of-arrival distortions occur with any sound that arrives from any direction other than directly in front, including the PA speaker positions to the left and right of the stage.
How much this difference matters depends, and that's a different discussion. Sometimes it won't matter, sometimes it will, sometimes a lot.
