Stretch is when a string elongates and then goes back to it's original length. Like stretching a rubber band and turning loose of it.

Creep is a permanent elongation of the string. Like grabbing hold of a piece of chewed gum and stretching it out. It STAYS stretched out.

The string and cables on your bow are under constant tension and they creep. If you know the factory specifications for your bow's axle to axle length and brace height, you can tell if you need to make adjustments to compensate for the creep by checking those measurements. If your bow is supposed to be 34" axle to axle with a 7" brace height and it checks 36" with a 6" brace height, you know it's time for maintenance.

Adjustments are made by pressing the bow and twisting the string and cables back to their specified lengths. So, this is something that you would need the pro shop to do. HOWEVER, I'd recommend watching them do it and learning how it's done. You can buy a portable press, like the Bowmaster, for about the cost of a couple of trips to the shop to have the work done for you. Then you can handle those little problems yourself.