Assignment Groups and Group Assignments are different features in Canvas:
Assignment Group
An Assignment Group in Canvas is a folder or a collection of Assignments.
If you do not have many assignments, you need not create more than one Assignment Group in your course.
Other than an organisational function, Assignment Groups can also be weighted.
Group Assignment
A Group Assignment, on the other hand, is an assignment where a group of students submits one assignment as a group. This feature works hand-in-hand with Groups in your course.
You set up a Group Assignment within the Assignment settings.
