ASP.net is not a coding language. It is a term to describe the (vast) area of the .net framework that allows you to write code directed to the web. The .net framework is chopped up into categories called namespaces. A typical namespace that would be described as to do with asp.net would be XML.
VB.net is different. It is one of several code languages that can communicate with the framework. Others include c# or j#. Cool thing is, is that your code, whatever language you use, gets compiled down into the same intermediate language (IL) which communicates with the .net framework.