You talk about these things as if you've teached them already? I know this is an "Advanced" tutorial, but these two terms seem to be referring to animation, so I would assume they get explained in this course! I know I could just ignore that and keep on going with the tutorial, but I want to UNDERSTAND everything, not just remember what to do.
This lesson explains IK vs FK:
https://cgcookie.com/lesson/discussion-fk-vs-ik
If you want to learn more about all the ins and outs of animation I highly recommend checking out the Animation Learning flow, which goes through all this terminology and techniques in high detail from beginner to pro.
https://cgcookie.com/flow/animation-in-blender
Here is a video I made before join CGC which explains exactly what you want to know ;)