This diagram demonstrates the project templates and project item templates that you can use when developing Web Parts in Visual Studio. While these templates have the same end result (a cool Web Part running SharePoint), the development experience can vary between working with code or using a designer to build the UI. For more information, see the following MSDN topics.
- Creating Web Parts for SharePoint
- Connect Web Parts in SharePoint 2010
- Creating SharePoint 2010 Web Parts That Can Read and Write Data to External Data Sources