Just wondering what the difference (if any) there is between the ArcGIS For Excel and and ArcGIS For Office?
The following blog discusses about the "ArcGIS for Excel" component.
Maps that provide fast time to value (esri.com)
"This NEW component is part of the ArcGIS for Microsoft 365 transition, that marks our complete transformation from locally managed installs to Software as a Service."
Please refer the above link for more details, especially the headers "What's changed" and What's new".