What is difference between 73 beetle and 74 super?

The windshield on the super beetle (and all super beetles) is rounded and makes a little dash board. The regular beetles windshield is flat and has no dash.

Irgleloid

Not true '71 and '72 Super beetles still have flat windshields, the curved windshield on a super beetle started in 1973 and also had non flat bigger plastic dashboard.