ArcInfo is the most complete desktop GIS. It includes all the functionality of ArcEditor and ArcView and adds advanced spatial analysis, extensive data manipulation, and high-end cartography tools. Organisations use the power of ArcInfo every day to create, edit, and analyse their data in order to make better decisions, faster. ArcInfo is the de facto standard for GIS. 

With ArcInfo, you can:

• Perform advanced GIS data analysis and modeling.
• Take advantage of tools designed for overlay analysis, proximity analysis, surface analysis, and raster processing and conversion.
• Publish and convert data in many formats.
• Create and manage personal geodatabases, multiuser geodatabases, and feature datasets.
• Use high-end cartography tools to generate professional-quality, publication-ready maps.
• Design customised symbols and place sophisticated annotation and labels on your maps

For more detail information on System Requirements, Whitepapers and other supporting resources visit the Esri site here

ArcInfo includes all the functionality of ArcEditor and adds advanced spatial analysis, data manipulation, and high-end cartography tools. It is the most complete desktop GIS.

Depending on what features you need, you can choose from among three license levels of ArcGIS Desktop (ArcInfo, ArcEditor, and ArcView). The ArcGIS Desktop products share the same common applications (ArcMap and ArcCatalog), user interface, and development environment. Additional functionality is unlocked as users move from ArcView to ArcEditor to ArcInfo.

The key features of ArcInfo are

• Advanced spatial analysis and modeling—Select from hundreds of geoprocessing tools to perform advanced GIS data analysis and modeling.
  • Perform overlay analysis including Union, Intersect, and Erase.
  • Perform proximity analysis including Buffer, Near, and Point Distance.
  • Perform surface analysis including Aspect, Hillshade, and Slope.
  • Perform raster processing and conversion.
• Extensive database management—Create and manage databases, define database schemas, and administer the integrity of databases.
  • Create personal geodatabases, multiuser geodatabases, and feature datasets.
  • Apply spatial analysis functions to transfer data into and out of databases.
  • Publish data in many formats.
  • Join adjacent datasets.
  • Perform batch processes on your databases.
• High-end cartography—Create professional-quality, publication-ready maps with simple wizards, predefined map templates, an extensive suite of map elements, and advanced drawing and symbolisation tools.
  • Apply cartographic text and labeling for atlaslike, publication-quality maps.
  • Design customised symbols, thematic categories, and style sheets for your map products.
  • Reduce manual editing time using intelligent rule-based annotation and label placement.
  • Use the functionality of the Maplex for ArcGIS extension (included with ArcInfo) for sophisticated annotation and label placement.
• Enabled for extensions—Add even more capabilities and extend the power of ArcInfo by using one or more of the many optional ArcGIS Desktop extensions. Analysis, productivity, and solution-based extensions allow you to perform extended tasks such as raster geoprocessing and three-dimensional analysis.

Download a more detailed comparison [PDF] of the ArcGIS Desktop product key features