EndNote Desktop is a software program that:
EndNote Basic is the free version of EndNote Desktop which allows up to 2GB of storage but has fewer features. It is for web only, not web and desktop and unlike EndNote Desktop, it does not allow PDF annotation or sharing.
Allows greater customization of output styles and import filters
Stored data can be accessed without an internet connection
Import citations from RIS files or added from OneSearch through the library. Citations can also be added from any webpage with the free EndNote Click extension.
Save and annotate PDFs
Bulk downloading of PDFs
Share papers and folders with external users
Microsoft Word integration
De-duping
Reference styles can be edited directly within the software
Expensive
Hard to switch between multiple computers
Limited web features
Earlier versions of EndNote do not allow for collaboration
Different versions have significant differences in them
Learning curve tends to be greater than other citation managers