An array list is essentially an array with methods to add items etc. (and you should use a generic list instead). It is a collection of items which can be accessed through an indexer (for example [0]). It implies a progression from one item to the next.
A linked list specifies a progression from one item to the next (Item a -> item b). You can get the same effect with an array list, but a linked list absolutely says what item is supposed to follow the previous one.
