They're not really two terms worth comparing like that -- a good PR is something that can contribute to a good ranking on an SERP. Ultimately SERPs are more important, but this is like saying a good website is more important than good HTML skills. Being skilled in HTML is one of the requisites to getting you a quality webiste, so calling attention to that is sort of a moot point.
SERP means search engine result page. it is the result page found by visitors when searching any item on google.
page rank is way to measure the weight of website.it indicate how many backlinkm the website have. ite range from 0-10