IPSC emphasises speed and accuracy in completing a course of fire; there are different divisions for different types of handgun ranging from off-the shelf Production guns (Glock, XD, etc) to highly tuned and customized "Open" guns with optics and compensators.
The only relevance to "practical" scenarios is you practice safe gun handling, while moving and throwing lead downrange as fast as possible with some degree of accuracy across multiple targets.
As someone said, "speed is a tactical advantage".
See
http://gpsl.org/faq.html for more detail - GPSAL shoots IPSC matches every Wednesday night in Lawrenceville. Many of the same folks shoot at the Bullseye in Cumming also.
I have not shot IDPA, but I understand emphasis is placed on shooting from behind cover, and other elements of style.
Neither is really "real-life" as the targets do not shoot back and they are both against the clock.