Vandy 3A and "Signature"

What does the "signature" package add to the Vanderstein 3A?  Is there a significant difference between the 3A model and the 3A Signature model?
sure...but my advice is to talk either to John at AudioConnection in Verona, New Jersey, or to Richard Vandersteen himself.   They both share the award for being tops in the help department.
Johnny R is a Agon member(audioconnection), so he would be easy to contact. Mr. V. is available, but he can be a bit brusque, so have your questions prepared in advance.
A quick Google pulled up this review:

I own the 3a sig's and can attest to their sound production.
Thanks; great link for comparison of the 3A and 3A Signature.
Changing model names brings more business.

Usually, a signature or special edition model will have an upgraded cross-over (speakers).
the original Signature had un upgraded crossover, different tweeter and other changes...and Vandersteen has made changes at times without changing the model number/name, as do many manufacturers 
Not a 3A Sig, but I own the 2A Sig 2 and love it. I believe the 3A Sig and my 2A sig 2 both uses the same tweeter and midrange driver of the Vandersteen 5A