1. vb is opps based, But dotnet is Completely supported for oops
2. In dot net we can develop console applications, web applications, mobile apps, smart device apps, But this was not possible in vb.
3. Lot of Advanced controls available in vb.net
4. in vb, only recordset concepts ( connection methods) are available, ex. DAO, ADO, RDO methods. But in dotnet ado.net(disconnected Database) method is also availble.
5. Cross language integration, Cross language Debugging and cross langauge inheritance is also possible in vb.net.
These are the main differences i know. Other than this there are lot of differences between vb and vb.net.