Apart from what others have said, these two construct (even if you can assume that $result will be 0 or 1) are not semantically equivalent if the expressions have side effects (for example, if one of them is a call to a subroutine that reads a file, computes a result, and removes the file before returning). In the array case, both expressions are always evaluated, whereas in the ternary operator only the one that corresponds to the decision value is. As a silly example, consider the following two expressions:

$result==0?"zero":5/$result;
("zero", 5/$result)[$result];
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The second one will produce a runtime error when $result==0.

--ZZamboni