How To: Run multiple types of ArcGIS software on the same machine
ArcGIS is written on a common code base. This means that once ArcGIS is installed, only the version of ArcGIS that was installed can be run unless you change it using the Desktop Administrator. This causes problems with users running Citrix or Windows Terminal Services.
Set the user environment variable ESRI_SOFTWARE_CLASS to the product you need to run.
For help with setting a system environment variable, see: How To: Edit an environment variable.
Viewer for ArcView
Editor for ArcEditor
Professional for ArcInfo
Note: The appropriate license must be available. Although the application title does not change, the application functionality will reflect the setting.