There is always a changelog. But there are different places.
As long we are in the RC mode, the changes are posted in the forum. The threads saying "here is a new version, please test" for example
http://forum.virtuemart.net/index.php?topic=115877.0.
If there is an official release, we write a news and add their the changes again. But a bit cleaned up and we try only to mention the more important ones.
and finally we have a changelog here
http://virtuemart.net/component/content/article/162-uncategorised/416-vm2liveupdateinformationThere we gather only the updates which are needed to keep the store running.
But I try to explain better.
The main difference of vm2.0 and vm2.1 is
- the customfields system. It is simplified and a lot more flexible for users and developers. It has also a better performance. It allows to override, disable or inherit each customfield. It also works now to use more than one customprototype on one page (that means we will add the add to cart button to the category browse views).
- the cart is working different. It stores a less data and creates the products on the fly. This means also that customfields can change every attribute of a product, for example the weight.
- vm2.1 runs on joomla 3 !