VirtueMart is a high performance enterprise-level e-commerce system which works within the Joomla framework. It fully utlises Joomla's advanced MVC development framework to enable it to be completely customised to your requirements. It also takes advantage of Joomla's advanced plugin framework to enable it's own plugin framework to expand the VirtueMart functionality even further.
OpenGlobal E-commerce is a developer on the VirtueMart project itself. These plugins expand and enhance the standard VirtueMart functionality.