Azure AD Join: This capability is exclusively available for Windows 10 and Windows 11 devices. It allows a device to be directly joined to the Azure AD tenant, enabling users to sign in to the device with their organizational credentials. Therefore, only Device1 (Windows 11) and Device2 (Windows 10) can be Azure AD joined. iOS and Linux devices do not support this functionality. Azure AD Registered: This process, also known as workplace join, creates a device object in Azure AD for personally owned devices (BYOD) to enable single sign-on (SSO) to company resources. It is supported on Windows 10/11, iOS, Android, and macOS. It is not supported for Linux. Consequently, Device1 (Windows 11), Device2 (Windows 10), and Device3 (iOS) can be registered in Azure AD.

1. Microsoft Learn | Azure AD joined devices: This official documentation specifies the supported operating systems for Azure AD Join.

Source: Microsoft Official Documentation

URL: https://learn.microsoft.com/en-us/azure/active-directory/devices/concept-azure-ad-join

Specific Section: Under the "Scenarios" and "Prerequisites" sections, it is explicitly stated that Azure AD Join applies to Windows 10 and newer devices.

2. Microsoft Learn | Azure AD registered devices: This document outlines the platforms that support Azure AD registration.

Source: Microsoft Official Documentation

URL: https://learn.microsoft.com/en-us/azure/active-directory/devices/concept-azure-adregister

Specific Section: The overview clearly states, "Azure AD registered devices are supported on a wide variety of Windows 10/11, iOS, Android, and macOS devices." It makes no mention of Linux as a supported platform for registration.