S.No. Ad Serving Ad Tracking
1 In this, the creative is hosted in an Ad server and Ad tags are shared with the Publisher In this, creative are hosted at the publisher end, only impressions and click tracker are shared by the advertiser/agency with the publisher.
2 It provides us all the details like impressions, clicks, verification and attribution data. It doesn’t provide verification and attribution data since creative are hosted at publisher end
3 We can exceed the weight limit of  creative since creative are hosted at our server In this we have to develop the creative as per publisher ad specs
4 The bigger advantage of ad serving over ad tracking is that it gives us control and check if our ad is appearing at the right place The control is completely with the publisher and for any change, the dependence is on publisher who is hosting the creative
5 Post impressions or post clicks activity is very important for advertisers today and is feasible when the ads are served at advertiser end Tracking does not help in detailed post impressions or post click activity data
6 Ad tags are little difficult to be manipulated, if done by the vendors it can be easily caught Ad trackers can be easily manipulated and can be misused
7 Reporting is seamless Maximum of the time you are dependent on publisher to get the final reports
8 Creative optimization is easy to manage as the creative control is the one who is serving it Creative optimization is managed by the publisher as they are the one who is serving the creatives