Workspaces contain docspaces, user groups and users.
Workspaces are a way for your account to be in multiple contexts, for example if you might have multiple companies. They are not a way for you to group users in 1 company.
User groups are a way to group users in 1 company, e.g. your departments. User groups allow you to assign access policies to certain docspaces so that only some users are able to see or edit content.
Docspaces are a way to group documents. They are similar to projects in your company. They can be assigned access policies so that only certain groups of people .
Users are members of 1 company.