Different waveforms of a song when recorded via aux vs when taken raw source file

When I record a song playing in my mobile via aux to my laptop, it has a different waveform from the one which I get when I drag the original source file of the track in the audacity.
Why is it so?
-Audacity 2.3.0 on Windows 8.1-

Your laptop probably doesn’t have “Aux-In”. Most laptops usually have a mono microphone input. The mic input is too sensitive for a line-level or headphone-level signal. And, the mic preamps built into laptops and soundcards tend to be low quality.

If you have a desktop computer with line-in, and if you get the levels set correctly, you can usually get good quality. But, the digital-to-analog-to-digital conversion is always imperfect, and some soundcards are noisy.

But… Don’t worry about the waveform if it sounds OK… Listen with your ears, not your eyes. :wink:

But my laptop has a stereo mic input as mentioned in the specifications. And I get stereo input in audacity with two channel waveform.
May be has to do with the conversion.
Also I get little bass when recorded through aux.