What is the difference between APR implementation of SSL and JSSE implementation of SSL on TOMCAT5.5

I'm configuring SSL to support HTTPS on TOMCAT 5.5, so I referred to http://tomcat.apache.org/tomcat-5.5-doc/ssl-howto.html, which elaborates on how to implement SSL.

This document describes two ways to implement SSL, namely the APR implementation and the JSSE implementation. I wonder what the difference between them is, including their shortcomings and advantages.