The directories containing the installers for the IFC for Revit projects are:
MISC - This contains associated files useful for IFC, such as updated Shared Parameters files.
2017 - This contains the installer combining the IFC Importer, IFC Exporter, and IFC Alternate Exporter UI for Revit sub-projects, compatible with the Revit 2017 and Revit LT 2017 series of products.
2016 - This contains the installer combining the IFC Importer, IFC Exporter, and IFC Alternate Exporter UI for Revit sub-projects, compatible with the Revit 2016 and Revit LT 2016 series of products.
2015 - This contains the installer combining the IFC Importer, IFC Exporter, and IFC Alternate Exporter UI for Revit sub-projects, compatible with the Revit 2015 and Revit LT 2015 series of products.
2014 UI - This contains the IFC Alternate Exporter UI for Revit installer compatible with the Revit 2014 and Revit LT 2014 series of products. There is no Revit 2012 version of this UI. This replaces the default IFC Export UI in Revit, and adds new functionality such as saving export configurations, and new export options such as saving to ifcXML and ifcZIP file formats.
2014 - This contains the IFC Exporter for Revit installer compatible with the Revit 2014 and Revit LT 2014 series of products. For more information on the difference between 2013 and 2014, check out the [What's new in 2014] section of the Wiki accessible from this site.
2013 UI - This contains the IFC Alternate Exporter UI for Revit installer compatible with the Revit 2013 series of products. There is no Revit 2012 version of this UI. This replaces the default IFC Export UI in Revit, and adds new functionality such as saving export configurations, and new export options such as saving to ifcXML and ifcZIP file formats.
2013 - This contains the IFC Exporter for Revit installer compatible with the Revit 2013 series of products. For more information on the difference between 2012 and 2013, check out the [What's new in 2013] section of the Wiki accessible from this site.
2012 - This contains the IFC Exporter for Revit installer compatible with the Revit 2012 series of products. The latest version is intended to be used with Revit 2012 Update Release 2, although earlier versions are available.