Structure for any type of SharePoint Project has differences:
1-in Microsoft you can find many templates for programming:
any type has it's own template: download them
for example for web parts:
Elements.xml
Contains information that is used by the Feature definition file in
your project to deploy the Web Part.
.webpart file
Provides information that SharePoint needs to display your Web Part in
a Web Part gallery.
Code File
Contains methods that add controls to the Web Part and generate custom
content within the Web Part.
you can download from here:
Visual Basic and C# SharePoint Templates
These templates appear under the Visual Basic/SharePoint or Visual C#/SharePoint subcategories, and may be further sorted into 2007 and 2010.
2- in CodePlex :
This project extends the Visual Studio 2010 SharePoint Project system
with advanced templates and tools.
3- SPSF
The SharePoint Software Factory is a Visual Studio Extension helping
SharePoint newbies, as well as experienced developers to create,
manage and deploy SharePoint solutions without having to know every
tiny XML and C# secret.
4- cksdev
This project extends the Visual Studio 2010 SharePoint project system
with advanced templates and tools.