When the callee cleans the arguments from the stack it needs to be known at compile time how many bytes the stack needs to be adjusted. Therefore, these calling conventions are not compatible with variable argument lists, eg. printf(). They may be, however, slightly more efficient as the code needed to unwind the stack does not need to be generated by the calling code.
Caller clean-up
In these conventions the caller cleans the arguments from the stack, which allows for variable argument lists, eg. printf().