There were two USPSA divisions back in the day. Open/Unlimited and Limited/Tactical. There was a Carry gun division for a while but it never took off. Actually there was one division for a long time. Just a heads up shooting match. Pick your poison and shoot it.

Production came out about 15 years ago and single stack has been around for a while also.

IDPA and IPSC are both good ways to get better at shooting under stress. Neither can replace actual training and neither should be viewed as real world training.