What is the difference between a compact state license and a traditional state license?

The compact license has all the rights and privileges of a regular state license, but it allows you to practice in any of the other (~37!) states in the compact. In general, the states that don’t have it are grouped in the West Coast and Northeast. So, if you plan to travel, you won’t need to hassle with getting a new state license every three months. Or, for example, you can have your primary job in Kansas City, MO, but pick up shifts in Kansas City, KS without extra licensing. Most states in the compact will allow you to automatically get the compact instead of just the state license, and there’s really no reason not to.