BBC standard DVD Set:
*Discs 1-4: All 11 episodes, about 50 minutes each, narration by David Attenborough
*Discs 1-4: A 10-minute "behind-the-scenes" featurette for each episode
*Disc 5: Planet Earth: The Future documentary (3 episodes x 50 minutes, or 150 minutes total)
BBC HD-DVD & Blu-Ray Sets:
*Discs 1-4: All 11 episodes, about 50 minutes each, narration by David Attenborough
So, each BBC episode is about 7 minutes longer than its Discovery Channel counterpart (and has a different narrator). This is most likely the only difference between the BBC standard and Discovery Channel DVD sets.
The BBC HD-DVD and Blu-Ray sets have the 50-minute BBC episodes, but remove the 5th disc (150 minutes) and the behind-the-scenes featurettes (110 minutes).
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