Im fairly new to using google Adwords, and have noticed that Google Adwords will report xxx amount of clicks, and Analytics will only report about 1/3 of those clicks. Adsense reports about the same amount as analytics. I dont think the page takes that long to load. So i think the analytics script runs. Is it possible for Adwords to count a click if the clicker hits the back button before the page even loads, or has a chance to load. Im just not very happy with the stats that are showing.
I am used to seeing up to 20% discrepancy in adwords VS analytics reports. What might explain your discrepancy is where the analytics tracking code is set in your page. If it is at the bottom of the HTML then it might not get loaded before the user leaves the page. This is especially true for multimedia pages that include heavy graphics and or video