our digital media business consists of our websites and mobile and video-on-demand ( 201cvod 201d ) services . our websites include network branded websites such as discovery.com , tlc.com and animalplanet.com , and other websites such as howstuffworks.com , an online source of explanations of how the world actually works ; treehugger.com , a comprehensive source for 201cgreen 201d news , solutions and product information ; and petfinder.com , a leading pet adoption destination . together , these websites attracted an average of 24 million cumulative unique monthly visitors , according to comscore , inc . in 2011 . international networks our international networks segment principally consists of national and pan-regional television networks . this segment generates revenues primarily from fees charged to operators who distribute our networks , which primarily include cable and dth satellite service providers , and from advertising sold on our television networks and websites . discovery channel , animal planet and tlc lead the international networks 2019 portfolio of television networks , which are distributed in virtually every pay-television market in the world through an infrastructure that includes operational centers in london , singapore and miami . international networks has one of the largest international distribution platforms of networks with one to twelve networks in more than 200 countries and territories around the world . at december 31 , 2011 , international networks operated over 150 unique distribution feeds in over 40 languages with channel feeds customized according to language needs and advertising sales opportunities . our international networks segment owns and operates the following television networks which reached the following number of subscribers as of december 31 , 2011 : education and other our education and other segment primarily includes the sale of curriculum-based product and service offerings and postproduction audio services . this segment generates revenues primarily from subscriptions charged to k-12 schools for access to an online suite of curriculum-based vod tools , professional development services , and to a lesser extent student assessment and publication of hardcopy curriculum-based content . our education business also participates in corporate partnerships , global brand and content licensing business with leading non-profits , foundations and trade associations . other businesses primarily include postproduction audio services that are provided to major motion picture studios , independent producers , broadcast networks , cable channels , advertising agencies , and interactive producers . content development our content development strategy is designed to increase viewership , maintain innovation and quality leadership , and provide value for our network distributors and advertising customers . substantially all content is sourced from a wide range of third-party producers , which includes some of the world 2019s leading nonfiction production companies with which we have developed long-standing relationships , as well as independent producers . our production arrangements fall into three categories : produced , coproduced and licensed . substantially all produced content includes programming which we engage third parties to develop and produce while we retain editorial control and own most or all of the rights in exchange for paying all development and production costs . coproduced content refers to program rights acquired that we have collaborated with third parties to finance and develop . coproduced programs are typically high-cost projects for which neither we nor our coproducers wish to bear the entire cost or productions in which the producer has already taken on an international broadcast partner . licensed content is comprised of films or series that have been previously produced by third parties . global networks international subscribers ( millions ) regional networks international subscribers ( millions ) .
what is the difference in millions of subscribers between discovery channel international subscribers and discovery science international subscribers?
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