Kindle Fire and Nook Tablet sales hurt Android more than iPad

Low-priced media tablets showed tremendous sales growth in 2011, with an estimated 7.5 million units combined from Amazon(s amzn) and Barnes & Noble(s bks). On Thursday, iHS noted that tablets from these two companies accounted for 11 percent of the total tablet market. This quick market-share grab didn’t hurt Apple iPads (s aapl) sales but instead held back sales of other Android tablets.

With its new iPad 2 debuting in the first half of 2011, Apple sold a total of 40.4 million units last year, accounting for 62 percent of all tablets sold. That’s down from the 87 percent tablet share in 2010, but Android tablet makers aren’t making up much of that difference. With sales of 6.1 million tablets, Samsung could only take 9 percent of the market, while Asus actually lost market share in the final quarter of 2011: sales were down 24 percent from the prior quarter.

Aside from offering a compelling device, Apple’s iPad continues to benefit from its strong ecosystem of apps and media content. Many of the same apps are available to iPhone and iPod touch users, for starters. And today, with the announcement of iOS-like features coming to OS X 10.8 this summer, the ecosystem tie-in is sure to keep iPad sales growing. Debuting a new iPad model, presumably next month, will continue the momentum.

On the other hand, the most successful Android tablets are Android in name only. The Kindle Fire and Nook Tablet have heavily modified user interfaces built upon Android’s smartphone software. Android tablets are still trying to find their way with Android 3.0 and 4.0. So why are the Kindle and Nook tablets beating out traditional Android tablets? For reasons similar to the iPad: stronger ecosystems when it comes to content.

Priced at $199 to $299, the Kindle and Nook don’t likely compete against the iPad when it comes to a purchase decision. Meaning: sales of these aren’t hurting the iPad much, if at all. The same can’t be said of the true Android tablets, which are still struggling to find an audience.