Similarities:
Both the tiger and Custard the dragon are wild creatures kept in captivity or confined surroundings. Neither is in its natural habitat — the tiger is locked in a zoo cage, while Custard lives as a pet in a house. Both animals appear meek and tame in their given situation; the tiger paces quietly at night, and Custard is mocked for being cowardly despite his fearsome appearance.
Differences:
The tiger in "A Tiger in the Zoo" is truly fierce but suppressed — he is a real, powerful predator whose freedom has been cruelly snatched. He feels rage and helplessness behind bars. Custard, however, is a fictional, comic character who is deliberately portrayed as timid despite his dragon form. He craves safety and comfort. Ironically, when danger arrives, Custard alone acts bravely and defeats the pirate. The tiger never gets a chance to show his true spirit freely.
Thus, both poems explore the gap between appearance and reality, but from opposite angles.
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