Why we get 2 groups created inside sharepoint when we create a new MS Teams

Question

I have created a new MS Teams from my MS Teams desktop application, I name the new MS Team as "TestUserPermission":

Now this has created a new SharePoint site + a new Office 365 group behind the scene, which is fine.

But what makes me got confused is that inside SharePoint site we got 2 groups/entitties named "TestUserPermision Members" and "TestUserPermission Owners", the first will be added inside the SharePoint member group while the other will be defined inside the site collection admin group, as follow:-

So what are those 2 entries? and what is the relation between those 2 entries and the Office 365 group? do any of them represent the Office 365 group which got created for us?

Answer 1

Here is the simple answer to your question:

When you create a new Team from Microsoft Teams or a new Team site from SharePoint, it creates a Microsoft 365 group. This Microsoft 365 group has 2 entities: Group Owners and Group Members as given in below image:

Relation between SharePoint groups and M365 group:

By default when M365 group is created it adds:

1. M365 group owners in SharePoint Site Collection Administrators
2. M365 group members in SharePoint default Members group which generally has name in format: <Site Title> Members

Answer 2

Within the SharePoint site, you have the owners, members and visitor groups. These are SharePoint groups. The members SharePoint group you have shown in your screenshot contains the Microsoft 365 group that was created when you created a Microsoft Team. It has the same name as your SharePoint members group. You can confirm this by clicking on that Microsoft 365 group and checking the object GUID against the object ID shown for your Microsoft 365 group inside Azure Active Directory.

The user that appears in your Site Collection Administrators group is a SP user which represents the owners of the Microsoft 365 group.