Why do these 2 soundtracks look so different?

Why do these 2 soundtracks look so different? They come from the same cassette tape. The top one I made years ago, and it sounds much better than the bottom one, which I just made. I can’t figure out what I did differently. Does anyone know? I am using v. 2.0.6 and Windows 7 Pro, 64-bit, and I downloaded the .exe file. Thanks!
Audacity - what's the difference.jpg

The upper one is at best, heavily compressed, and at worst, badly clipped. Judging from the appearance alone, I would guess that it is badly clipped, whereas the lower track is only a little bit clipped. However, the clipping may sound worse on the second track if the first track was clipped due to overloading an analog input. The lower track has digital clipping (exceeds 0 dB) which tends to sound “crunchy” and very unpleasant.

Thanks very much for your answer, Steve. At the risk of sounding like an ignoramus, what is clipping? I see that it is not under “Effects” in Audacity.

It’s a kind of distortion in which the tops and bottoms of the waveform get cut (“clipped”) off.
More about it here: http://en.wikipedia.org/wiki/Clipping_(audio)

Thanks much. I just watched a video on clipping on youtube, so I see the top and bottom of the waves are flattened due to excessive volume. I will check out your Wikipedia reference. If you’re not careful, you learn something every day. Thanks again, Steve!