Question: I was just curious as to what exactly Sprite Kit Restitution actually configures? I know that it configures some behavior about an SKPhysicsBody's parameters, but how does the behavior differ?

Answer: 
Sprite Kit Physicsbody Restitution is defined as

> 
> "a property describing how much energy a body retains when it bounces 
>  off of another body, basically a fancy way of saying "bounciness""
>  -IOS Games by Tutorials
> 
> 
> 

Also an [excerpt from the IOS Developer Library (Apple Docs)](https://developer.apple.com/library/ios/documentation/SpriteKit/Reference/SKPhysicsBody_Ref/Reference/Reference.html#//apple_ref/occ/instp/SKPhysicsBody/restitution)

> 
> This property is used to determine how much energy the physics body 
>  loses when it bounces off another object. 
>  The property must be a value between 0.0 and 1.0. The default value is 0.2.
> 
> 
> 

Also just note that the compiler won't complain if you supply values outside of the range from (0.0 to 1.0); however, think about what it will mean to have a value greater than 1, for example. The body would actually end a collision with MORE energy than it had initially. That's not very realistic behavior and often times will very quickly break your physics simulation.
Restitution basically equates to an object's "bounciness"