You can check the release notes too.
Few links from outside that I make reference are like for older veriosn like 12 :
http://www.docstoc.com/docs/16844876/Teradata-Database-Release-12-0 for 12. I collate with other ppts, points too for RFIs ,RFPs and knowledge of systems :).
Used to work much in v2r5, 13.. and 14.. and less of 12 version :)
I am not sure if there is any architectural change in TD 12-14.
Adding different functionalities has been there but not architectural changes.
Dieter can confirm this.