Both Magento and Virtumart platforms use PHP tools. But features like composer are inbuilt in magento framework whereas it is just in virtualmart for name’s sake.
Composer is there to manage PHP dependencies. In composer.json developers define dependencies, which are then handled automatically by composer.
In addition, it can be used to manage Magento extensions.
However, in Joomla, it only serves the purpose of installation, without becoming part of the framework as in the case of Magento.
image Source- https://www.gavik.com/documentation/joomla/third-party-extensions/virtuemart/install-virtuemart
Magento has a console utility that saves and manages 1000’s of caches. Whereas, such functionality is missing in Virtualmart.