And what are the pro's con's of using either?
I actually saw it in Netbeans under Project Properties > Libraries for Java Applications. We have two tabs, one for compile time libraries and run time libraries, and it looks like we can add a library to either independent of each other
There is no such a thing as compile time libraries vs. runtime libraries
Perhaps your mixing some concepts.
In Java the libraries to be used are statically validated at compile time and also validated at runtime.
For instance if you want to use IterableMap specified in the Apache Collections library. The compiler validates "at compile time" you are invoking a method that exist in that class.
But the compiler doesn't link or do much anything with that library, you still need it at runtime. So, when your code executes, the java runtime, search for that class again, and invoke the method the compiler verified existed.
And that what there is.
As others have stated, you are confusing concepts. I think what you are really trying to understand is what Maven refers to as dependency scope. Sometimes you only need a dependency at compile time because you expect it to be provided at runtime, and sometimes you need it at runtime but not compile time.