I've never understood this myself; yet I understand a lot about electronics. How a VA is not a Watt I am unsure; for now I just take it as face value that they are different units. If the GP or someone else would kindly explain better than Wikipedia does, I would appreciate it.
It's probably just some semantic detail I am overlooking. For example, for the longest time I did not understand why wall outlets are polarized. I mean, since alternating current flows in both directions, how can AC be polarized unless it has a DC offset? After a long time, I came to understand on my own it's not about positive/negative charges, but just an indicator of which conductor is hot and which leads to ground to complete the circuit.