[Lil bastard]

Downforce and Lift are not the same thing at all.

Lift is created when air passing over the car (moving faster than the air underneath) drops in pressure. That means the slower air running under the car has less counteracting force and so the car 'lifts'.

Downforce is air which is redirected by a Wing upward, pushing the Wing (and the car it's attached to) downward. This keeps the force of the air over and under the car in equilibirum - it counteracts the effect of the low pressure created on top of the car (but does not prevent it).

A Spoiler slows down (or 'spoils') the airflow going over the top of the car so that no low pressure (or less of it) is created. It does not counteract lift, it prevents it.

To many, the differences are subtle, but they are distinct.

Race cars use Wings and downforce. They do this because either a Spoiler or a Wing create drag, which slows the car - it's a compromise between maximum speed and control. But, in order for a Spoiler to be effective at race speeds at preventing lift, it would have to be much bigger than a Wing would be to counteract lift. So it would create more drag than a Wing and have a greater impact on speed. Also, a Wing is more adaptable to changes in Temp, Humidity, Track condition because it's angle of attack can be easily altered. A Spoiler could not.

On a Boxster, the stock Spoiler is effective. The aftermarket Wings are no more so, only look prettier to some people. Also, it allows them to personalize their car. But, they are not better or more effective - some may even be less so.