I've heard many different things about this and I've read several different answers too.. And even though I somehow feel that I know the answer, I still want to make sure that I actually do understand it..
From how I understand things, SERP is:
Google's search engine results based on a certain keyword?
Meanwhile PageRank (PR) is a scale from 1-10 your website will get from Google?
Feel free to enlighten me with whatever you've got!