A light fixture is one that is wired directly into an electrical box in the ceiling and is operated by a wall switch. The wall switch can be a simple toggle switch or a dimmer switch, to give you full control of the mood that you are creating.
Some hanging lights are fixtures and some are swags. A swag lamp isn't a permanent fixture. They normally have 2 ceiling hangers that allow the cord to "swag" across the ceiling, to position the lamp over the area that you wish to have light. They are thus fully adjustable.