What are the main differences between a Set collection and an array in programming?

A Set collection and an array (List) differ in the following main characteristics:

• Uniqueness of elements: Set stores only unique elements; duplicates are automatically ignored. An array can contain repeated values.
• Order of elements: In most implementations, Set does not guarantee the order of elements, whereas an array preserves the order of insertion.
• Access by index: In an array, you can access an element by its index, but in a Set — no, since it is not indexed.
• Performance of operations: Checking for the presence of an element in a Set is usually faster (O(1) for hash sets) than in an array (O(n)).

Example in Dart (Flutter):

var list = [1, 2, 2, 3];
var set = {1, 2, 2, 3};

print(list); // [1, 2, 2, 3]
print(set);  // {1, 2, 3}