Complex sentence: The Wool Pooh is the "twin brother" of Winnie the Pooh, as Byron describes him but the Wool Pooh is actually Grandma Sands' pronunciation of whirlpool.
Split into simpler sentences: The Wool Pooh is the "twin brother" of Winnie the Pooh, as Byron describes him. But the Wool Pooh is actually Grandma Sands' pronunciation of whirlpool.