The two main roles for users in Flint are owners and members. A person can be a member in one group and an owner in another. And these roles affect their permissions in groups and tutors (see here for more on groups and tutors).
Members
Members of a group can use any public tutors made in the group they are in, or unlisted and private tutors if they have the link or are invited to them, respectively. Members can also create and share tutors.
Members can create subgroups within a group, where they will be owners of the subgroup.
Owners
Owners of a group can see group and tutor analytics in addition to everything members of a group can do.
Owners of a tutor can duplicate tutors to share with other groups they are owners of.