'What is the difference between declaring an array using "[]"or"{}"?

In Google Apps Script what is the difference between declaring an array using "[]"or"{}"? For example:

function myFunction(){
var colors = []
var colors2={}
}

Thanks for any help



Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution Source