Hello BigHeavyQ,
I will try and make it more simple.
Reformed Epistemology
Reformed Epistemology seeks to justify someone's belief in God by arguing that such a belief is properly basic, and as such no other justification is needed because properly basic beliefs are so basic that they have the nature of being axiomatic (self-evident). Axioms are assumed rather than proved. For instance, the law of non-contradiction may be considered a properly basic belief. The law of non-contradiction is not proved (to prove it you must already be assuming it), but rather is assumed. Reformed Epistemology argues that belief in God is a properly basic belief like the law of non-contradiction and as such one does not need any other evidence to justify holding the belief. Someone once flippantly said that Reformed Epistemology seeks for reasons why it does not need reasons.
Presuppositionalism
The idea of presuppositional apologetics is to realize that we all have fundamental, core commitments that are not proved but rather assumed which allow us to answer questions about what is real, how we can know, and what is right and wrong. The presuppositionalist argues that unless one assumes the Christian God, then the foundation is not sufficient for there to be knowledge or anything. In other words, God is the ultimate axiom needed to make sense of the world. This is not what Reformed Epistemologists argue - although they would agree God is the necessary foundation. They only make the point that belief in God is justified because it is properly basic. The presuppositionalist argues in a much stronger manner. They argue that God is so properly basic that we are justified in believing in Him because apart from Him we cannot know anything or even predicate anything.
I hope this helps a little.
Brian