We've debated this topic before, but here are some common definitions that most should agree with. Goodah's links may explain it better, but I'll throw this in anyway.
The stroker prefers more slide, and chooses to play straighter than the cranker most of the time. The stroker does not muscle the ball. His arm swing his relaxed. Because he has less leverage and earlier timing than the cranker, he does not have as many revs, but instead relies on accuracy and shot repetition. The stroker favors 45 degree axis rotation.
Examples: Norm Duke, Mike Scroggins
The cranker prefers less slide, often planting his foot to prevent sliding. His timing is later than the stroker's, and he tends to muscle the ball. By planting his foot early, the cranker has powerful leverage that allows him to rotate the ball faster than the stroker, even though his hand release may be the same. The cranker favors 90 degree (or full side) rotation.
Examples: Robert Smith, Brian Himmler
The tweener can do some of each--playing straight or hooking from deep. The tweener has more revs than the stroker, but less than the cranker. Tweener's favor both 45 and 90 degree axis rotation depending on how they choose to play the lanes.
Examples: Walter Ray, Chris Barnes
The spinner is a whole different thing. The spinner spins the ball like a top, going straight down the middle of the lane. He uses a light ball (12 pounds, typically) so it will deflect and cause chaos. I tried this method, and it is hard! Throwing a ball perfectly straight is not easy. Try spinning a ball in a straight line! Now that's difficult. That shot is not favored here in the United States.
Examples: Some Japanese folks.