Audition is mainly a multitrack recording station also called a DAW, “Digital Audio Workstation” and a 2 track audio mastering station in one piece of software. Audition will allow you to record as many inputs at once as the audio interface your using, meaning if you have a 16 channel in Firewire interface you can record 16 independent channels at the same time. Great for recording bands using close micing techniques at the same time.
Soundbooth also has limited multitracks but is intended for audio with video production or simple 2 track recording.