Huge difference between 409.1 and VCDS. VCDS works with all the latest cars! 409, being from September of 2004 obviously doesn't.
But I suppose you're really asking about VCDS-Lite. Please read the official product announcement
here.
I'll sum up the differences between 409.1 and VCDS-Lite:
* VCDS-Lite is Windows Vista and 7 compatible. 409 was rather fidgety to get working on those.
* VCDS-Lite has an improved activation scheme which doesn't require a new license file every time you re-install Windows or format your hard drive.
* VCDS-Lite has much improved documentation (Label Files) for the cars it works with (which is basically all the models which don't require CAN for diagnostics).
* VCDS-Lite is faster and has a built-in Latency test to
help with those situations where communications are not stable.
* VCDS-Lite is full supported, all versions of "VAG-COM" are now obsolete.
If you registered VAG-COM 311 or 409, an update to VCDS-Lite is FREE.
-Uwe-