Java - Can a class access a private field of its nested class?

as I understand it private fields can only be accessed in the class that they are defined.

I have this code for a rudimentary singly linked list:

public class LinkedList {
    private class Node {
        private String data;
        private Node next;

        private Node(String data, Node nextNode) {
            this.data = data;
            this.next = nextNode;
        }
    }
    private Node head;
    public LinkedList(String data) {
        // Create head node, set next node null
        head = new Node(data, null);
    }
    public void add(String data){
        Node currentNode = head;
        while(currentNode.next != null){
            currentNode = currentNode.next;
        }
        currentNode.next = new Node(data, null);
    }
    public void printList(){
        Node currentNode = head;
        System.out.println(currentNode.data);
        while(currentNode.next != null){
            currentNode = currentNode.next;
            System.out.println(currentNode.data);
        }
    }
}

It appears to run and work just fine, but I am trying to figure out why I can access the 'data' and 'next' fields of class Node in my functions in class LinkedList.

Adding onto this, is a nested class the same thing as a subclass defined with the 'extends' keyword?

Cheers, thanks for the help.

edit: just adding onto this question, in other implementations of linked lists I see people defining two separate classes for node, and list. It made more sense to me for node to be a nested class of linkedlist. If this is not entirely correct please let me know...