Your personal locker area is not course-specific. You can access the locker from anywhere in Learning Environment and store all of your files together.
Group lockers are restricted locker areas where members of a group can share files. Any group member can modify files posted in group locker areas.
Group lockers have the same options as regular lockers with the following exceptions:
Click Locker on the navbar.
You can also access the Locker tool from the Classlist or Groups tool.
Click Locker on your course navbar, then click Group Lockers.
Note You can only access a group locker from the course offering it applies to.
Links:
[1] http://staging.docs.d2l/en/taxonomy/term/3