There are a few fundamental differences when working with arrays in PHP and
Ruby. PHP uses the versatile array data type to handle both numerically
ordered collections and associative key/value pair collections. Ruby uses two
different objects -- Array for ordered collections, and Hash for
associative style collections.
In many of the array function examples we interchangeably use both Ruby arrays and hashes to display the closest Ruby equivalent.
It is important to note that hashes in Ruby are unordered collections. If the order of elements is important to the operation, you will need to use Ruby arrays.