The various account types dictate what a user is allowed to do on the site. Choose the appropriate role for the specific permissions a user should have.
Administrator: Nothing is off limits (except on network-based, multisite configurations, administrators cannot manage plugins or remove network features).
Editor: Has access to all posts, pages, comments, categories, tags, and links; but cannot see or export Forms or Form submission; manage menus, and other site admin settings.
Author: Can write, upload photos to, edit, and publish their own posts.
Contributor: Has no publishing or uploading capability, but can write and edit their own posts until they are published.
Subscriber: Gives user a login to your website with no privileges, but means they can view Private pages if they are logged in – for example, for a private board member page.
Each user role is capable of everything that a less powerful role is capable of. In other words, Editors can do everything Authors can do, Authors can do everything Contributors can do, and so on.