Here are the different user types and permissions members of an asset library can have:
Owner: Owners have all the rights listed below as well as the right to assign people with roles and permissions.
Administrator: As an administrator, you can reach the "Content Administration" page where you upload images, create collections, share collections, invite people, assign roles and permissions.
User: As a user, you only have access to the public page on the web. There you can download the images in the collections that are published.
Contributor: A contributor is a user that has been invited to upload and edit specific collections and their content. They will only see the collections they have been invited to.
IT Admin: This user type has the same access as an administrator, but they are also the main contact in charge of integrations and Azure AD connections.
Billing Rights: The owner of the asset library can choose who has billing rights. If you have billing rights you have permission to perform actions that result in changes to your invoice, like adding new users.
In the Pickit add-ins for PowerPoint, Word and Teams, all users have the same experience regardless of the roles or permissions. It is only on the web where it will affect which role you have been assigned.