What is: Administrator
In most cases there is only one administrator. In the case of a WordPress multisite installation, some of the capabilities of the admin role are assigned to the super admin role. The super admin could modify themes, add new users, add and remove plugins, and administer the site network while the roles of the admin would only be concerned with managing a single site.
Ideally, you should have as few Administrators as possible. If you’re an agency or freelance web developer who manages a site for a client, you should be the sole Administrator. You can still give your client access to add/edit content, moderate comments, etc (see Editor or Author roles). But without Administrator access, they won’t be able to mess with settings, plugins and themes, which could all negatively impact the site.
This Conditional Tag checks if the Dashboard or the administration panel is attempting to be displayed. It is a boolean function that will return true if the URL being accessed is in the admin section, or false for a front-end page.
What is: Administrator?
The Administrator can also upgrade the theme, upgrade the version of WordPress, upgrade plugins, change the theme, install or deactivate plugins and access and modify WordPress’s core coding. The Administrator can also change all of the settings for a WordPress site. Administrators can also manage comments and content produced by other users, including deleting it. Essentially, there are no restrictions on what the Administrator can do with regards to a single WordPress website.