Every keyblade has a different keychain and design on it, with its own type of power. Sora, Roxas, and Xion's keyblades are generally referred to as the Keyblade of Light. King Mickey's is the Dark Keyblade, which is why they have similar designs but swapped colors (i.e. silver blade/gold hilt on Sora's, gold blade/silver hilt on Mickey's). Keyblades also are somewhat sentient, as they choose who wields them based on the strength of the wielder's heart.
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