Two identical guitars are played by two persons to give notes of same pitch . Will they differ in quality ? give me reason

No, if and only if the guitars are exactly identical in shape and size, and also produces the same pitch.

I'm not a guitar player, but can't the individual player influence to note slightly by the tension with which he/she applies to the finger holding down the string? More importantly, the point on the string where it is plucked will determine the nature of the overtones generated, and the player can change that.

Two identical guitars are played by two persons to give notes of same pitch . Will they differ in quality ? give me reason

This question is a bit vague. Could you give a little more background? Is it maybe that the guitars are being played simultaneously?

If your question is what it is than there is a lot of room for player interpretation while playing the same notes on a guitar (or any other instrument)

Also there is no such thing as "identical" guitars, every guitar sounds a little different due to age, usage, small construction differences, etc. Air temperature, air pressure have impact too. If we look at this from a cold, science point of view, heres what it would look like. If you put 2 identical guitars played by a robot into a studio, they would sound the same. Except they wouldn't, for the reasons above.

 

Edit: Just to give you an example of what might be relevant here, here's a "phase shift" example:

 

 

If the 2 guitars are being played (almost) simultaneously and their "phase shift" is lets say 1/10 of a second you would hear a slight echo effect. If the shift would be larger, lets say half a second - you would hear a significantly stronger echo effect. Hope this helps.

Edited September 25, 20169 yr by koti

Ya, phase difference is a point, but it will not effect the quality of the sound produced. Consider the two guitar players in two different rooms, none can hear the other one. In such a case the quality of the note will be same.

A theoretical guitar string may have a perfect sine wave as it vibrates, but that vibration causes resonant vibration within the instrument, which complicates the waveform. Every piece of the instrument will have some small effect on the form of the sound wave emitted, and there is no way that any two wooden instruments could produce exactly the same changes in the sound. They can be extremely close - maybe even enough that a human ear couldn't detect the difference - but they will be different.

Such resonance and reverberation will alter the quality of sound. But, the OP says that the two guitars are identical.