Custom Group: You will need to manually add references to the group.
A Smart Group: You will need to define your search terms so that the references will be added or updated automatically within your EndNote Library.
A Group Set: A group set serves as the name of a header. You can create Custom Groups and Smart Groups under a Group Set.
Note: Smart Groups and Group Sets do not show up in EndNote Online, however they do sync to your other desktop EndNote installations.
To create a group:
1. At the top of EndNote, go to Groups
2. Select the type of group you want to create
3. Name the group.
4. Now the group is ready for you to add references to.