To get any changes that have been checked in for a solution/project, you can use the appropriate update command Update Solution or Update Project. When you update a solution/project, StarTeam updates the project source files with the latest revisions from the repository. If files have been added to or removed from Visual Studio, your local solution/project will reflect these changes too. If a file is in a merge state, StarTeam asks if you want to merge the changes. You can also update solutions and projects using the StarTeam context menu commands in the Solution Explorer.
Committing a project commits any changes to the project and the source files in the project, creating new revisions of these files in the repository. If files have been added to or removed from your Visual Studio project, the project in the repository reflects these changes when you commit it.