Categories and Tags are designed to organize your work and facilitate campaign search for your team members.
Team admin can create/edit/view/delete/assign all categories (except General which is the default category) and tags, other team members can view/assign categories and tags only for campaigns and flow they have access to.
Use Categories to group your campaigns in the reports. One campaign can belong only to one category. You can create an unlimited number of categories. Manage your categories under Settings > Categories menu.
Use Tags to add colored labels to your campaigns and flow. Then you can filter your campaigns and flows inside reports. Type tag name in Search field and see only campaigns or flows with that tag. Manage your tags under Settings > Tags menu.