#. Team Site With an Office 365 Group #. Team Site Without an Office 365 Group #. Communication Site #. Classic Sites
What is Team Site (With Office 365 Group) and Why Team Site is Used
You can think of it as a development site or project site where team working on this project will collaborate with each other.
You can not only share documents but also you can also enhance your teams collaboration with using some other apps like Teams, Outlook, Planner that are linked to Team Site.
What is Communication Site and Why Communication Site is Used
This site is not used for collaboration between Teams. You can Think of it as a One-Way Communication Site.
As in Team Site Communication Sites does not have apps like Teams, Outlook, Planner
Team Site (Without Office 365 Group)
To Create a Team Site without Office 365 group You will need to have the SharePoint Admin Role. It uses the same site template as if Team Site with office 365 group but it is not connected to Office 365 Group