They are both graphics libraries. AWT is the old-fashioned library that uses the windowing system of the operating system to control its objects. Swing is the new library that is written almost entirely in Java.
A2:
Lightweight means that they consume fewer resources than their heavyweight AWT counterparts.
A3:
A JTextField object is limited in size and intended for use when a single piece of data is to be entered. A JTextArea object expects to contain many lines of text.
A4:
The ListSelectionListener interface is used to determine which item in the list was selected.
