I have always witnessed little difference between adwords clicks to my websites and google analytics referral figure.But from last few days it has increased too much like Adwords -> Site targeted campaign is showing 147 Adwords -> Keywords targeted campaign is showing 182 But urchin is only showing 137 referrals from pagead2.googlesyndication.com Where is problem and which is more reliable data?
My understanding is that referrals from pagead2.googlesyndication.com refer to content targeted (site targeted) adword placements only. Search targeted referrals are mixed in with general Google referrals unless you use tracking parameters to differentiate them. Therefore your analytics figure of 137 is reasonably close to the AdWords figure of 147.