I have less information about share point (only basic info). Microsoft released SharePoint for web developers. Microsoft also said SharePoint has compatibility with other .NET t
If you just want to create a website, go for ASP.net.
However, if your company has a SharePoint installation and you want to integrate with that, you should go for SharePoint.
SharePoint is build on ASP.net, but has many extensions that allow data to be shared throughout the company.
However, if you are just building a website and don't need all that, ASP.net is the way to go.