Hi @ElieAT, Based on your needs, you can target policies to both device groups, and user groups you create. There are also 2 pre-created groups; All devices, (all intune enrolled devices) and all users (all Intune licensed users).
If you want to apply a policy (setting) on a device, regardless of who’s signed in, use a devices group. Users do not need to sign-in on a device for these policies and/or apps to be applied/installed when you use a device group
Create and assign user groups when you want that your policies/apps to be applied to a specific user (group). It will apply on any applicable device the user signs in.
Also have a look at Assign device profiles in Microsoft Intune | Microsoft Docs
When ever you can, you should use the pre-created groups. When you want a more granular control, create your own groups.
Hope this helps
