What are the differences between team observers and participants?
Team observers are more like guests to your team. They have view-only access, and can't create, edit records, or create new applets. However, they can comment on and see the full activity of any applets that you invite them to.
Team members are your regular team members. They have full access to the applets that they are a part of. Members can also create new applets in the workspace scope, and invite team members to participate. (However, they cannot invite people who are outside the team.)