Groups and cohorts are both collections of students. There are several differences between them. We can sum up these differences in one sentence, that is; cohorts enable administrators to enroll and unenroll students en masse, whereas groups enable teachers to manage students during a class.

Think of a cohort as a group of students working together through the same academic curriculum. For example, a group of students all enrolled in the same course. Think of a group as a subset of students enrolled in a course. Groups are used to manage various activities within a course.

Cohort is a system-wide or course category-wide set of students.

There is a small amount of overlap between what you can do with a cohort and a group. However, the differences are large enough that you would not want to substitute one for the other.