I pulled both samples down, and normalized them to the same level. There was approximately 20dB difference between the peaks of the two files. The Garageband sample was -4.4db, the Audition sample was -24.8dB. That's a huge difference.
Once the levels were equalized, I heard the following:
The Garageband sample has more bass, could be due to microphone placement as it sounds like proximity effect, but it also has a LOT more hiss.
The Audition sample lacks the low end, but is much quieter in the non speaking parts. It also seems to have a bit of phasing or something going on, a bit of "swishing sound". I don't have Audition, so I can't tell what the source might be. Did you run any noise reduction on the clip? You said it was the raw audio.
There was some strange static noise in the Audition sample. Since I know nothing about your setup, I can't speculate where the noise came from. There may be similar static sound on the Garageband sample, but with the hiss level so high, it is hard to really hear it.
Were these clips done at the same time? If not, maybe set up your mic and load Garageband first and do a quick read, then load Audition and do the same with identical setups and phrases. Try to set levels to give similar readings. That might help us diagnose things further.
