Key Difference: Google Adsense is an advertising program by Google. It allows websites to publish ads in order to generate revenue. The ads can be automatic text, image, video, or interactive media advertisements. While Adsense is an advertisement program for publishers, DoubleClick develops and provides Internet ad serving services. Doubleclick is an Ad Server or channel through which Ads can be served.

Google Adsense is an advertising program by Google. It allows websites to publish ads in order to generate revenue. The ads can be automatic text, image, video, or interactive media advertisements. The ads are associated with certain keywords, and will be shown if those keywords are associated with the site’s content. The ads are also shown on basis of the targeted audience and their geographical location. This ensures that the ads are relevant to the viewers and hence the viewers are more likely to click on them.

The ads are administered, sorted, and maintained by Google and can generate revenue on either a per-click or per-impression basis. A pay per click (PPC) system is where the publisher is paid according to the number of times that the viewers have clicked on the ad. Whereas, a cost per impression (CPI) is there the publisher is paid for how many people have viewed the ad on their site. CPI is usually calculated on the basis on a thousand views.

Adsense is currently one of the most popular advertising programs out there. This is due to the fact that the ads displayed through their network are usually relevant, and tries to be non-intrusive. Adsense is also particularly popular with small websites that do not have the resources for developing advertising sales programs and sales people to generate revenue with.

DoubleClick, on the other hand, is a subsidiary of Google. While Adsense is a advertisement program for publishers, DoubleClick develops and provides Internet ad serving services. This means that it provides software to web sites and advertisers that can be used to serve ads, count the ads, and choose the ads that will make the website or advertiser most money. The software can also monitor the progress of different advertising campaigns.

DoubleClick’s main focus is on uploading ads and reporting their performance. It offers features such as streamlined ad trafficking, inventory management, revenue optimization, and granular reporting. DoubleClick has two main products, DFA (Doubleclick for Advertisers) and DFP (Doubleclick For Publishers).

DoubleClick was originally founded in 1995 by Kevin O'Connor and Dwight Merriman. It was formerly listed as "DCLK" on the NASDAQ. In July 2005, DoubleClick was acquired by private equity firms Hellman & Friedman and JMI Equity. Google eventually acquired DoubleClick for US$3.1 billion in March 2008.

The main difference between Adsense and Doubleclick is essentially that Doubleclick is an Ad Server or channel through which Ads can be served. In terms of AdSense, DFP acts as the intermediary to do so, or serve AdSense Ads. With Google Adsense, a publisher can display contextually-relevant, unobtrusive Google ads on the website's pages to earn money. Whereas, with Doubleclick, the publisher can manage directly-sold and network-based online advertising inventory in addition to Google AdSense. Hence, it can be said that Doubleclick is more of an advertising agency, rather than an advertising program like Adsense.

Today, Doubleclick counts companies like Microsoft, General Motors, Coca-Cola, Motorola, L'Oréal, Palm, Inc., Apple Inc., Visa USA, Nike, Carlsberg and various others as customers. Whereas, Adsense is used by any small publisher to some of the biggest websites out there.

Comparison between Adsense and Doubleclick:

Image Courtesy: googletoday.net, freshegg.co.uk