In an inverting closed-loop opamp we know that gain is calculated based on resistor values (Rf/Rin). In this case, both amps have a gain of 10 (Av1=10k/1k, Av2=1k/100).
As for responses to noise, guess which one is more efficient in reducing noise? (Shake your iPhone to inject noise into the signal and measure which circuit amplifies noise spikes the most)
*Note that with both circuits, Vin and Vout is of the same amplitude (10mV and 100mV respectively).
Noise in a circuit is proportional to resistance (impedance) and temperature, therefore it makes better sense to build a circuit with less resistance (or impedance) to achieve best results.
