For both PHP and JS, there really isn't a difference; you're just given some basic data structures that handle pretty much everything under the sun, and you go from there. You can have an array with numeric keys (list), or you can have an array with string keys (dictionary), and it's only in your implementation that will determine if you use it as an iterative structure or as a kind of hash-lookup structure.
While PHP does have some advanced data structures provided by SPL, and some JS implementations offer typed arrays and such, they're rarely used in the wild for various reasons. I think the main reason, though, is probably that they're not really needed for 99.9% of web apps.